Insulin-regulated aminopeptidase (IRAP) inhibitors and uses thereof

ABSTRACT

The present invention relates to inhibitors of insulin-regulated aminopeptidase (IRAP) and methods for inhibiting same, as well as compositions comprising said inhibitors. In particular, the inhibitors of the present invention may be useful in therapeutic applications including enhancing memory and learning functions.

FIELD OF THE INVENTION

The present invention relates to novel compounds for use as inhibitorsof insulin-regulated aminopeptidase (IRAP) and methods for inhibitingsame, as well as compositions comprising said compounds. In particular,the compounds of the present invention may be useful in therapeuticapplications including enhancing memory and learning functions.

DESCRIPTION OF THE PRIOR ART

The reference in this specification to any prior publication (orinformation derived from it), or to any matter which is known, is not,and should not be taken as an acknowledgment or admission or any form ofsuggestion that that prior publication (or information derived from it)or known matter forms part of the common general knowledge in the fieldof endeavour to which this specification relates.

Insulin-regulated aminopeptidase (MAP) is a 165 kDa glycoprotein that iswidely distributed in many tissues including fat, muscles, kidney,adrenal, lung and heart (Keller et al., 1995; Rogi et al., 1996; Zhanget al., 1999). In the brain, it occurs as a smaller 140 kDa protein,probably due to differential glycosylation (Keller et al., 1995; Zhanget al., 1999). It is a type II integral membrane protein belonging tothe M1 family of zinc-dependent metallopeptidases and possesses a largeC-terminal extracellular tail which contains the catalytic site, asingle transmembrane domain and a smaller N-terminal intracellulardomain (Keller et al., 1995; Rogi et al., 1996). Initially cloned from arat epididymal fat pad cDNA library as a marker protein (vp165) for aspecialised vesicle containing the insulin-responsive glucosetransporter GLUT4 (Keller et al., 1995), the same protein was clonedconcurrently from human placental cDNA library as oxytocinase (Rogi etal., 1996), an enzyme which was thought to have an important role indegrading oxytocin. The AT₄ receptor has also recently been identifiedas the transmembrane enzyme insulin regulated aminopeptidase (IRAP) viamass spectral analysis of tryptic peptides generated from AT₄ receptorprotein purified from bovine adrenal membranes (Albiston et al., 2001).Analysis of the biochemical and pharmacological properties of IRAPconfirm that it is, in fact, the AT₄ receptor (Albiston et al., 2001).Although isolated by three independent groups from different tissuesources and thought to subserve distinct physiological roles, propertiesand characteristics of this protein remain consistent.

The AT₄ ligands, angiotensin IV (Ang IV), its analogues Nle-Ang IV andNorleucinal Ang IV, and the structurally distinct peptide LVV-hemorphin7 (LVV-H7), all bind with high affinity and relative specificity to apharmacologically distinct binding site, termed the AT₄ receptor. Allthe AT₄ ligands, Ang IV, Nle-Ang IV, and LVV-H7, were demonstrated invitro to be inhibitors of the aminopeptidase activity of IRAP asassessed by cleavage of the synthetic substrate Leu-β-naphthylamide(Albiston et al., 2001; Lew et al., 2003). Both Ang IV and LVV-H7display competitive kinetics indicating that AT₄ ligands mediate theireffects by binding to the catalytic site of IRAP. Using the same systemit has also been demonstrated that although the peptides Ang IV andLVV-H7 bind to the catalytic site they are not cleaved by IRAP (Lew etal., 2003).

Central administration of the peptide AT₄ ligands, Mg IV, its morestable analogues, or LVV-H7, in normal animals has been shown to lead toimproved performance of memory tasks in both passive avoidance andspatial learning paradigms. The initial effects were observed in thepassive avoidance paradigm in rats where an intracerebro-ventriculardose (1 nmol) of Ang IV increased the latency in re-entering the darkchamber after an aversive stimulus (Braszko et al., 1988; Wright et al.,1993; Wright et al., 1996). Chronic infusion (6 days) of an Ang IVanalogue into the lateral ventricle of rats at a dose of between 0.1 and0.5 nmol/h enhanced performance in the swim maze, a spatial memoryparadigm. In the Barnes maze, another spatial learning task, treatmentof rats with 100 pmoles or 1 nmol of the peptide AT₄ ligands, Nle¹-AngIV or LVV-H7, decreased the time taken to achieve learner criteria inthis paradigm (Lee et al., 2004). Control animals treated withartificial cerebrospinal fluid took 7 days to achieve learner criteria,whereas animals treated with Nle¹-Ang IV or LVV-H7, at a concentrationof either 100 pmoles or 1 nmole, achieved learner criteria in 3-4 days(Lee et al., 2004). This observation strongly indicates that the twopeptides tested not only improved memory, but also enhanced spatiallearning.

Not only did peptide AT₄ ligands enhance memory and learning in normalanimals, the peptides reversed memory deficits induced (1) chemically bya muscarinic antagonist or (2) mechanically by knife-cut lesion of theperforant pathway. A more stable analogue of Ang IV, Nle-Ang IV, givenacutely into the lateral ventricles, reversed the memory deficitsinduced by the muscarinic receptor antagonist, scopolamine, in a spatiallearning paradigm (Pederson et al., 1998; Pederson et al., 2001). In theswim maze paradigm, memory deficits induced by bilateral perforantpathway lesion can be reversed by an acute dose (1 nmol) of another AngIV analogue, Norleucinal Ang IV (Wright et al., 1999). The other AT₄ligand, LVV-H7, given acutely prior to the conditioning trial in thepassive avoidance paradigm, has also been found to reverse the memorydeficit induced by scopolamine (Albiston et al., 2004).

The mechanisms for IRAP inhibitors facilitating memory are not fullyunderstood, but recent studies implicate neuroendocrine mechanisms ofaction. Inhibition of IRAP may extend the half-life of neuropeptidesthat modify learning and memory processes (Albiston, 2003). A number ofIRAP peptide substrates including arginine-vasopressin, oxytocin,met-enkephalin, somatostatin, dynorphin and lys-bradykinin havepreviously been associated with memory (Herbst, 1997; Lew, 2003).Moreover, studies have shown that peptidergic neurotransmission isaltered in neurodegenerative diseases leading to memory loss. IRAP isfound in high concentrations in brain regions involved in processingcognitive function including the cerebral cortex, hippocampus, basalforebrain and amygdale (Fernando, 2005) where it is co-expressed inneurons with the glucose transporter, GLUT4. It has recently beendemonstrated that IRAP inhibitors increase activity-evoked glucoseuptake into the pyramidal neurons of the hippocampus (J neurochemsubmitted). Glucose is a potent modulator of learning and memory in bothhumans and rodents with increases in glucose demand in the hippocampusoccurring during memory processing (McNay, 2000; Dash, 2006). Therefore,one potential mechanism by which compounds may facilitate memory isthrough the potentiation of glucose uptake into neurons.

IRAP therefore provides a target for the development of agents which mayenhance or improve memory and learning. Accordingly, inhibitors of IRAP,which may disrupt or interfere with IRAP functional activity may haveuseful therapeutic and/or prophylactic applications in the treatment ofcognitive and memory disorders or in enhancing memory and learning.

WO 2006/026832 discloses a class of benzo-fused compounds for use asIRAP inhibitors. Nevertheless, there remains the need for identificationof compounds which may be useful in the treatment or prevention ofmemory disorders or improve memory or learning.

SUMMARY OF THE INVENTION

Throughout this specification and the claims which follow, unless thecontext requires otherwise, the word “comprise”, and variations such as“comprises” and “comprising”, will be understood to imply the inclusionof a stated integer or step or group of integers or steps but not theexclusion of any other integer or step or group of integers or steps.

The singular forms “a”, “an” and “the” include plural aspects unless thecontext clearly dictates otherwise.

It has now been found that certain benzo-fused compounds within thescope of the disclosure of WO 2006/026832 have a surprisingly improvedIRAP inhibitory activity when compared to the most active compoundexemplified therein.

Accordingly, in a first aspect, the present invention provides acompound of Formula (I)

wherein A is aryl, heteroaryl carbocyclyl or heterocyclyl, each of whichmay be optionally substituted, when R¹ is NHCOR₈; or

-   -   quinolinyl, isoquinolinyl, cinnolinyl, quinazolinyl,        quinoxalinyl, 1,8-naphthyridyl, phthalazinyl or pteridinyl, each        of which may be optionally substituted, when R¹ is NR⁷R⁸,        NHCOR₈, N(COR₈)₂, N(COR₇)(COR₈), N═CHOR₈ or N═CHR₈;    -   X is O, NR′ or S, wherein R′ is hydrogen, optionally substituted        alkyl, optionally substituted alkenyl, optionally substituted        alkynyl, optionally substituted aryl, optionally substituted        acyl, optionally substituted heteroaryl, optionally substituted        carbocyclyl or optionally substituted heterocyclyl;    -   R⁷ and R⁸ are independently selected from hydrogen, optionally        substituted alkyl, optionally substituted aryl, or R⁷ and R⁸,        together with the nitrogen atom to which they are attached form        a 3-8-membered ring which may be optionally substituted;    -   R² is CN, CO₂R⁹, C(O)O(O)R⁹, C(O)R⁹ or C(O)NR⁹R¹⁰ wherein R⁹ and        R¹⁰ are independently selected from alkyl, alkenyl, alkynyl,        aryl, heteroaryl, carbocyclyl, heterocyclyl, each of which may        be optionally substituted, and hydrogen; or R⁹ and R¹⁰, together        with the nitrogen atom to which they are attached, form a        3-8-membered ring which may be optionally substituted;    -   R³-R⁶ are independently selected from hydrogen, halo, nitro,        cyano alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl,        carbocyclyl, hydroxy, alkoxy, alkenyloxy, alkynyloxy,        alkynyloxy, aryloxy, heteroaryloxy, heterocyclyloxy, amino,        acyl, acyloxy, carboxy, carboxyester, methylenedioxy, amido,        thio, alkylthio, alkenylthio, alkynylthio, arylthio,        heteroarylthio, heterocyclylthio, carbocyclylthio, acylthio and        azido, each of which may be optionally substituted where        appropriate, or any two adjacent R³-R⁶, together with the atoms        to which they are attached, form a 3-8-membered ring which may        be optionally substituted; and    -   Y is hydrogen or C₁₋₁₀alkyl,        or a pharmaceutically acceptable salt or solvate thereof.

In another aspect, the present invention provides a method forinhibiting IRAP activity which comprises contacting IRAP with aninhibitory amount of a compound of formula (I), or a pharmaceuticallyacceptable salt or solvate thereof. Inhibition of IRAP activity can beperformed in vitro or in vivo, such as in vivo in a subject. Theinvention therefore also provides a method for inhibiting IRAP activityin a subject in need thereof, which comprises administering to saidsubject an inhibitory effective amount of a compound of formula (I), ora pharmaceutically acceptable salt or solvate thereof.

Compounds described herein may be useful in treating a disease orcondition in which excessive or undesirable IRAP activity plays a role.Thus, the invention further provides a method for treating a disease orcondition in which IRAP activity is implicated, in a subject in needthereof, comprising the step of administering to said subject aneffective amount of a compound of formula (I), or a pharmaceuticallyacceptable salt or solvate thereof. The invention also provides for theuse of a compound of formula (I), or a pharmaceutically acceptable saltor solvate thereof in the manufacture of a medicament for treating adisease or condition in which IRAP activity is implicated, as well asfor the use of a compound of formula (I), or a pharmaceuticallyacceptable salt or solvate thereof, for treating a disease or conditionin which IRAP activity is implicated. In one embodiment, the disease isAlzheimer's disease.

As described above, IRAP inhibitors have been shown to improve memoryand enhance spatial learning as well as reversing memory deficits.

Accordingly, in another aspect, the present invention provides a methodfor enhancing memory and/or learning in a subject, comprising the stepof administering to said subject a compound of formula (I) or apharmaceutically acceptable salt or solvate thereof. The invention thusalso provides for the use of a compound of formula (I), or apharmaceutically acceptable salt or solvate thereof in the manufactureof a medicament for enhancing memory and/or learning in a subject, aswell as for the use of a compound of formula (I), or a pharmaceuticallyacceptable salt or solvate thereof, for enhancing memory and/or learningin a subject.

The invention also provides agents and compositions comprising acompound according to Formula (I) or a pharmaceutically acceptable saltor solvate thereof together with a pharmaceutically acceptable carrieror excipient.

DESCRIPTION OF THE INVENTION

As used herein, the term “alkyl” or “alk”, used either alone or incompound words denotes straight chain, or branched alkyl, preferablyC₁₋₂₀ alkyl, e.g. C₁₋₁₀ or C₁₋₆. Examples of straight chain and branchedalkyl include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl,t-butyl, n-pentyl, 1,2-dimethylpropyl, 1,1-dimethyl-propyl, hexyl,4-methylpentyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl,1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl,1,2-dimethylbutyl, 1,3-dimethylbutyl, 1,2,2,-trimethylpropyl,1,1,2-trimethylpropyl, heptyl, 5-methylhexyl, 1-methylhexyl,2,2-dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl,1,2-dimethylpentyl, 1,3-dimethylpentyl, 1,4-dimethyl-pentyl,1,2,3-trimethylbutyl, 1,1,2-trimethylbutyl, 1,1,3-trimethylbutyl, octyl,6-methylheptyl, 1-methylheptyl, 1,1,3,3-tetramethylbutyl, nonyl, 1-, 2-,3-, 4-, 5-, 6- or 7-methyl-octyl, 1-, 2-, 3-, 4- or 5-ethylheptyl, 1-,2- or 3-propylhexyl, decyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- and8-methylnonyl, 1-, 2-, 3-, 4-, 5- or 6-ethyloctyl, 1-, 2-, 3- or4-propylheptyl, undecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8- or9-methyldecyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-ethylnonyl, 1-, 2-, 3-, 4- or5-propyloctyl, 1-, 2- or 3-butylheptyl, 1-pentylhexyl, dodecyl, 1-, 2-,3-, 4-, 5-, 6-, 7-, 8-, 9- or 10-methylundecyl, 1-, 2-, 3-, 4-, 5-, 6-,7- or 8-ethyldecyl, 1-, 2-, 3-, 4-, 5- or 6-propylnonyl, 1-, 2-, 3- or4-butyloctyl, 1-2-pentylheptyl and the like. Where an alkyl group isreferred to generally as “propyl”, butyl” etc, it will be understoodthat this can refer to any of straight or branched isomers whereappropriate. An alkyl group may be optionally substituted by one or moreoptional substituents as herein defined.

The term “alkenyl” as used herein denotes groups formed from straightchain or branched hydrocarbon residues containing at least one carbon tocarbon double bond including ethylenically mono-, di- orpoly-unsaturated alkyl groups as previously defined, preferably C₂₋₂₀alkenyl (e.g. C₂₋₁₀ or C₂₋₆). Examples of alkenyl include vinyl, allyl,1-methylvinyl, butenyl, iso-butenyl, 3-methyl-2-butenyl, 1-pentenyl,1-hexenyl, 3-hexenyl, 1-heptenyl, 3-heptenyl, 1-octenyl, 1-nonenyl,2-nonenyl, 3-nonenyl, 1-decenyl, 3-decenyl, 1,3-butadienyl,1-4,pentadienyl, 1,3-hexadienyl and 1,4-hexadienyl. An alkenyl group maybe optionally substituted by one or more optional substituents as hereindefined.

As used herein the term “alkynyl” denotes groups formed from straightchain or branched hydrocarbon residues containing at least onecarbon-carbon triple bond including ethynically mono-, di- orpoly-unsaturated alkyl groups as previously defined. Unless the numberof carbon atoms is specified the term preferably refers to C₂₋₂₀ alkynyl(e.g. C₂₋₁₀ or C₂₋₆). Examples include ethynyl, 1-propynyl, 2-propynyl,and butynyl isomers, and pentynyl isomers. An alkynyl group may beoptionally substituted by one or more optional substituents as hereindefined.

Terms written as “[group]oxy” refer to a particular group when linked byoxygen, for example, the terms “alkoxy”, “alkenoxy”, “alkynoxy” and“aryloxy” and “acyloxy” respectively denote alkyl, alkenyl, alkynyl,aryl and acyl groups as hereinbefore defined when linked by an oxygenatom. Terms written as “[group]thio” refer to a particular group whenlinked by sulfur, for example, the terms “alkylthio”, “alkenylthio”,alkynylthio” and “arylthio” respectively denote alkyl, alkenyl, alkynyl,aryl groups as hereinbefore defined when linked by a sulfur atom.Similarly, a term written as “[groupA]groupB” is intended to refer to agroupA when linked by a divalent form of groupB, for example,“hydroxyalkyl” is a hydroxy group when linked by an alkylene group.

The term “halogen.” (“halo”) denotes fluorine, chlorine, bromine oriodine (fluoro, chloro, bromo or iodo).

The term “aryl” (or “carboaryl)”, or the abbreviated form “ar” used incompound words such as “aralkyl”, denotes any of mono-, bi- orpolcyclic, (including conjugated and fused) hydrocarbon ring systemscontaining an aromatic residue. Examples of aryl include phenyl,biphenyl, terphenyl, quaterphenyl, naphthyl, tetrahydronaphthyl(tetralinyl), anthracenyl, dihydroanthracenyl, benzanthracenyl,dibenzanthracenyl, phenanthrenyl, fluorenyl, pyrenyl, idenyl,isoindenyl, indanyl, azulenyl and chrysenyl. Particular examples of arylinclude phenyl and naphthyl. An aryl group may be optionally substitutedby one or more optional substituents as herein defined.

The term “carbocyclyl” includes any of non-aromatic monocyclic, bicyclicand polycyclic, (including fused, bridged or conjugated) hydrocarbonresidues, e.g. C₃₋₂₀ (such as C₃₋₁₀ or C₃₋₈). The rings may besaturated, for example cycloalkyl, or may possess one or more doublebonds (cycloalkenyl) and/or one or more triple bonds (cycloalkynyl).Examples of particular carbocyclyl are monocyclic 5-6-membered orbicyclic 9-10 membered ring systems. Suitable examples includecyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, cyclononyl, cyclodecyl, cyclopentenyl, cyclohexenyl,cyclooctenyl, cyclopentadienyl, cyclohexadienyl, cyclooctatetraenyl anddecalinyl. A carbocyclyl group may be optionally substituted by one ormore optional substituents as herein defined. In particular, amonocarbocyclyl group may be substituted by a bridging group to form abicyclic bridged group.

The term “heterocyclyl” when used alone or in compound words includesany of monocyclic, bicyclic or polycyclic, (including fuse, bridged orconjugated) hydrocarbon residues, such as C₃₋₂₀ (e.g. C₃₋₁₀ or C₃₋₈)wherein one or more carbon atoms are independently replaced by aheteroatom so as to provide a group containing a non-aromatic heteroatomcontaining ring. Suitable heteroatoms include, O, N, S, P and Se,particularly O, N and S. Where two or more carbon atoms are replaced,this may be by two or more of the same heteroatom or by differentheteroatoms. The heterocyclyl group may be saturated or partiallyunsaturated, e.g. possess one or more double bonds. Particularlypreferred heterocyclyl are monocyclic 5-6- and bicyclic 9-10-memberedheterocyclyl. Suitable examples of heterocyclyl groups may includeazridinyl, oxiranyl, thiiranyl, azetidinyl, oxetanyl, thietanyl,2H-pyrrolyl, pyrrolidinyl, 1-, 2- and 3-pyrrolinyl, piperidyl,piperazinyl, morpholinyl, indolinyl, imidazolidinyl, imidazolinyl,pyrazolidinyl, thiomorpholinyl, dioxanyl, tetrahydrofuranyl,tetrahydropyranyl, tetrahydropyrrolyl, tetrahydrothiophenyl(tetramethylene sulfide), pyrazolinyl, dioxalanyl, thiazolidinyl,isoxazolidinyl, dihydropyranyl, oxazinyl, thiazinyl, thiomorpholinyl,oxathianyl, dithianyl, trioxanyl, thiadiazinyl, dithiazinyl, trithianyl,azepinyl, oxepinyl, thiepinyl, indenyl, indanyl, 3H-indolyl,isoindolinyl, 4H-quinolazinyl, chromenyl, chromanyl, isochromanyl,benzoxazinyl (2H-1,3, 2H-1,4-, 1H-2,3-, 4H-3,1-4H-1,4) pyranyl anddihydropyranyl. A heterocyclyl group may be optionally substituted byone or more optional substituents as defined herein.

The term “heteroaryl” includes any of monocyclic, bicyclic, polycyclic,(fused or conjugated) hydrocarbon residues, wherein one or more carbonatoms are replaced by a heteroatom so as to provide a residue having atleast one aromatic heteroatom-containing ring. Exemplary heteroaryl have3-20 ring atoms, e.g. 3-10. Particularly preferred heteroaryl are 5-6monocyclic and 9-10 membered bicyclic ring systems. Suitable heteroatomsinclude, O, N, S, P and Se, particularly O, N and S. Where two or morecarbon atoms are replaced, this may be by two or more of the sameheteroatom or by different heteroatoms. Suitable examples of heteroarylgroups may include pyridyl, pyrrolyl, thienyl, imidazolyl, furanyl,benzothienyl, isobenzothienyl, benzofuranyl, isobenzofuranyl, indolyl,isoindolyl, pyrazolyl, pyrazinyl, pyrimidinyl, pyridazinyl, indolizinyl,quinolyl, isoquinolyl, phthalazinyl, 1,5-naphthyridinyl, quinozalinyl,quinazolinyl, quinolinyl, oxazolyl, thiazolyl, isothiazolyl, isoxazolyl,triazolyl, oxadialzolyl, oxatriazolyl, triazinyl, tetrazolyl andfurazanyl. A heteroaryl group may be optionally substituted by one ormore optional substituents as defined herein.

The term “acyl” either alone or in compound words denotes a groupcontaining the moiety C═O (and not being a carboxylic acid, ester oramide) Preferred acyl includes C(O)—R, wherein R is hydrogen or analkyl, alkenyl, alkynyl, aryl, heteroaryl, carbocyclyl, or heterocyclylresidue. Examples of acyl include formyl, straight chain or branchedalkanoyl (e.g. C₁₋₂₀) such as, acetyl, propanoyl, butanoyl,2-methylpropanoyl, pentanoyl, 2,2-dimethylpropanoyl, hexanoyl,heptanoyl, octanoyl, nonanoyl, decanoyl, undecanoyl, dodecanoyl,tridecanoyl, tetradecanoyl, pentadecanoyl, hexadecanoyl, heptadecanoyl,octadecanoyl, nonadecanoyl and icosanoyl; cycloalkylcarbonyl such ascyclopropylcarbonyl cyclobutylcarbonyl, cyclopentylcarbonyl andcyclohexylcarbonyl; aroyl such as benzoyl, toluoyl and naphthoyl;aralkanoyl such as phenylalkanoyl (e.g. phenylacetyl, phenylpropanoyl,phenylbutanoyl, phenylisobutylyl, phenylpentanoyl and phenylhexanoyl)and naphthylalkanoyl (e.g. naphthylacetyl, naphthylpropanoyl andnaphthylbutanoyl]; aralkenoyl such as phenylalkenoyl (e.g.phenylpropenoyl, phenylbutenoyl, phenylmethacryloyl, phenylpentenoyl andphenylhexenoyl and naphthylalkenoyl (e.g. naphthylpropenoyl,naphthylbutenoyl and naphthylpentenoyl); aryloxyalkanoyl such asphenoxyacetyl and phenoxypropionyl; arylthiocarbamoyl such asphenylthiocarbamoyl; arylglyoxyloyl such as phenylglyoxyloyl andnaphthylglyoxyloyl; arylsulfonyl such as phenylsulfonyl andnapthylsulfonyl; heterocycliccarbonyl; heterocyclicalkanoyl such asthienylacetyl, thienylpropanoyl, thienylbutanoyl, thienylpentanoyl,thienylhexanoyl, thiazolylacetyl, thiadiazolylacetyl andtetrazolylacetyl; heterocyclicalkenoyl such as heterocyclicpropenoyl,heterocyclicbutenoyl, heterocyclicpentenoyl and heterocyclichexenoyl;and heterocyclicglyoxyloyl such as thiazolyglyoxyloyl andthienylglyoxyloyl. The R residue may be optionally substituted asdescribed herein.

In this specification “optionally substituted” is taken to mean that agroup may be unsubstituted or further substituted or fused (so as toform a condensed bi- or polycyclic group) with one, two, three or moreof organic and inorganic groups, including those selected from: alkyl,alkenyl, alkynyl, carbocyclyl, aryl, heterocyclyl, heteroaryl, acyl,aralkyl, alkylaryl, alkylheterocyclyl, alkylheteroaryl,alkylcarbocyclyl, halo, haloalkyl, haloalkenyl, haloalkynyl, haloaryl,halocarbocyclyl, haloheterocyclyl, haloheteroaryl, haloacyl,haloaryalkyl, hydroxy, hydroxyalkyl, hydroxyalkenyl, hydroxyalkynyl,hydroxycarbocyclyl, hydroxyaryl, hydroxyheterocyclyl, hydroxyheteroaryl,hydroxyacyl, hydroxyaralkyl, alkoxyalkyl, alkoxyalkenyl, alkoxyalkynyl,alkoxycarbocyclyl, alkoxyaryl, alkoxyheterocyclyl, alkoxyheteroaryl,alkoxyacyl, alkoxyaralkyl, alkoxy, alkenyloxy, alkynyloxy, aryloxy,carbocyclyloxy, aralkyloxy, heteroaryloxy, heterocyclyloxy, acyloxy,haloalkoxy, haloalkenyloxy, haloalkynyloxy, haloaryloxy,halocarbocyclyloxy, haloaralkyloxy, haloheteroaryloxy,haloheterocyclyloxy, haloacyloxy, nitro, nitroalkyl, nitroalkenyl,nitroalkynyl, nitroaryl, nitroheterocyclyl, nitroheteroaryl,nitrocarbocyclyl, nitroacyl, nitroaralkyl, amino (NH₂), alkylamino,dialkylamino, alkenylamino, alkynylamino, arylamino, diarylamino,aralkylamino, diaralkylamino, acylamino, diacylamino, heterocyclamino,heteroarylamino, carboxy, carboxyester, amido, alkylsulphonyloxy,arylsulphenyloxy, alkylsulphenyl, arylsulphenyl, thio, alkylthio,alkenylthio, alkynylthio, arylthio, aralkylthio, carbocyclylthio,heterocyclylthio, heteroarylthio, acylthio, sulfoxide, sulfonyl,sulfonamido, aminoalkyl, aminoalkenyl, aminoalkynyl, aminocarbocyclyl,aminoaryl, aminoheterocyclyl, aminoheteroaryl, aminoacyl, aminoaralkyl,thioalkyl, thioalkenyl, thioalkynyl, thiocarbocyclyl, thioaryl,thioheterocyclyl, thioheteroaryl, thioacyl, thioaralkyl, carboxyalkyl,carboxyalkenyl, carboxyalkynyl, carboxycarbocyclyl, carboxyaryl,carboxyheterocyclyl, carboxyheteroaryl, carboxyacyl, carboxyaralkyl,carboxyesteralkyl, carboxyesteralkenyl, carboxyesteralkynyl,carboxyestercarbocyclyl, carboxyesteraryl, carboxyesterheterocyclyl,carboxyesterheteroaryl, carboxyesteracyl, carboxyesteraralkyl,amidoalkyl, amidoalkenyl, amidoalkynyl, amidocarbocyclyl, amidoaryl,amidoheterocyclyl, amidoheteroaryl, amidoacyl, amidoaralkyl,formylalkyl, formylalkenyl, formylalkynyl, formylcarbocyclyl,formylaryl, formylheterocyclyl, formylheteroaryl, formylacyl,formylaralkyl, acylalkyl, acylalkenyl, acylalkynyl, acylcarbocyclyl,acylaryl, acylheterocyclyl, acylheteroaryl, acylacyl, acylaralkyl,sulfoxidealkyl, sulfoxidealkenyl, sulfoxidealkynyl,sulfoxidecarbocyclyl, sulfoxidearyl, sulfoxideheterocyclyl,sulfoxideheteroaryl, sulfoxideacyl, sulfoxidearalkyl, sulfonylalkyl,sulfonylalkenyl, sulfonylalkynyl, sulfonylcarbocyclyl, sulfonylaryl,sulfonylheterocyclyl, sulfonylheteroaryl, sulfonylacyl, sulfonylaralkyl,sulfonamidoalkyl, sulfonamidoalkenyl, sulfonamidoalkynyl,sulfonamidocarbocyclyl, sulfonamidoaryl, sulfonamidoheterocyclyl,sulfonamidoheteroaryl, sulfonamidoacyl, sulfonamidoaralkyl, nitroalkyl,nitroalkenyl, nitroalkynyl, nitrocarbocyclyl, nitroaryl,nitroheterocyclyl, nitroheteroaryl, nitroacyl, nitroaralkyl, cyano,sulfate, sulfonate, phosphonate and phosphate groups. Optionalsubstitution may also be taken to refer to where a CH₂ group in a chainor ring is replaced by a carbonyl group (C═O) or a thiocarbonyl group(C═S), where 2 adjacent or non-adjacent carbon atoms (e.g. 1,2- or 1,3)are substituted by one end each of a —O—(CH₂)_(s)—O— or—NR^(x)—(CH₂)_(s)—NR^(x)— group, wherein s is 1 or 2 and each R^(x) isindependently H or C₁₋₆alkyl, and where 2 adjacent or non-adjacentatoms, independently selected from C and N, are substituted by one endeach of a C₁₋₅alkylene or C₂₋₅alkenylene group (so as to form a bridgedgroup).

Exemplary optional substituents include those selected from: alkyl,(e.g. C₁₋₆alkyl such as methyl, ethyl, propyl, butyl), cycloalkyl (e.g.C₃₋₆cycloalkyl, such as cyclopropyl, cyclobutyl, cyclopentyl orcyclohexyl), hydroxyalkyl (e.g. hydroxyC₁₋₆alkyl, such as hydroxymethyl,hydroxyethyl, hydroxypropyl), alkoxyalkyl (e.g. C₁₋₆alkoxyC₁₋₆alkyl,such as methoxymethyl, methoxyethyl, methoxypropyl, ethoxymethyl,ethoxyethyl, ethoxypropyl), alkoxy (e.g. C₁₋₆alkoxy, such as methoxy,ethoxy, propoxy, butoxy), alkoxyalkoxy (e.g. C₁₋₆alkoxyC₁₋₆ alkoxy, suchas methoxymethoxy, methoxyethoxy, methoxypropoxy, ethoxymethoxy,ethoxyethoxy, ethoxypropoxy, propoxymethoxy, propoxyethoxy,propoxypropoxy) cycloalkoxy (e.g. cyclopropoxy, cyclobutoxy,cyclopentoxyl, cyclohexyloxy), halo, haloalkyl(e.g. haloC₁₋₆alkyl, suchas chloromethyl, difluoromethyl, trifluoromethyl, trichloromethyl,tribromomethyl), haloalkoxy (e.g. haloC₁₋₆alkoxy), hydroxy, thio (—SH),sulfonyl, sulfonamido, phenyl (which itself may be further substitutede.g., by one or more C₁₋₆alkyl, halo, hydroxy, hydroxyC₁₋₆alkyl,C₁₋₆alkoxy, C₁₋₆alkoxyC₁₋₆alkyl, C₁₋₆alkoxyC₁₋₆alkoxy, haloC₁₋₆alkyl,haloC₁₋₆alkoxy, cyano, nitro, OC(O)C₁₋₆alkyl, NH₂, NHC₁₋₆alkyl,NHC(O)C₁₋₆alkyl and NC₁₋₆alkylC₁₋₆alkyl), benzyl (wherein benzyl itselfmay be further substituted e.g., by one or more of C₁₋₆alkyl, halo,hydroxy, hydroxyC₁₋₆alkyl, C₁₋₆alkoxy, C₁₋₆alkoxyC₁₋₆alkyl,C₁₋₆alkoxyC₁₋₆alkoxy, haloC₁₋₆alkyl, haloC₁₋₆alkoxy, cyano, nitro,OC(O)C₁₋₆alkyl, NH₂, NHC₁₋₆alkyl, NHC(O)C₁₋₆alkyl andNC₁₋₆alkylC₁₋₆alkyl), phenoxy (wherein phenyl itself may be furthersubstituted e.g., by one or more of C₁₋₆alkyl, halo, hydroxy,hydroxyC₁₋₆alkyl, C₁₋₆alkoxy, C₁₋₆alkoxyC₁₋₆alkyl, C₁₋₆alkoxyC₁₋₆alkoxy,haloC₁₋₆alkyl, haloC₁₋₆alkoxy, cyano, nitro, OC(O)C₁₋₆alkyl, NH₂,NHC₁₋₆alkyl, NHC(O)C₁₋₆alkyl and NC₁₋₆alkylC₁₋₆alkyl), benzyloxy(wherein benzyl itself may be further substituted e.g., by one or moreof C₁₋₆alkyl, halo, hydroxy, hydroxyC₁₋₆alkyl, C₁₋₆alkoxy,C₁₋₆alkoxyC₁₋₆alkyl, C₁₋₆alkoxyC₁₋₆alkoxy, haloC₁₋₆alkyl,haloC₁₋₆alkoxy, cyano, nitro, OC(O)C₁₋₆alkyl, NH₂, NHC₁₋₆alkyl,NHC(O)C₁₋₆alkyl and NC₁₋₆alkylC₁₋₆alkyl), NH₂, alkylamino (e.g.—NHC₁₋₆alkyl, such as methylamino, ethylamino, propylamino etc),dialkylamino (e.g. —NH(C₁₋₆alkyl)₂, such as dimethylamino, diethylamino,dipropylamino), acylamino (e.g. —NHC(O)C₁₋₆alkyl, such as —NHC(O)CH₃),phenylamino (i.e. —NHphenyl, wherein phenyl itself may be furthersubstituted e.g., by one or more of C₁₋₆alkyl, halo, hydroxy,hydroxyC₁₋₆alkyl, hydroxyC₁₋₆alkoxy C₁₋₆alkoxy, C₁₋₆alkoxyC₁₋₆alkyl,C₁₋₆alkoxyC₁₋₆alkoxy, haloC₁₋₆alkyl, haloC₁₋₆alkoxy, cyano, nitro,OC(O)C₁₋₆alkyl, NH₂, NHC₁₋₆alkyl, NHC(O)C₁₋₆alkyl andNC₁₋₆alkylC₁₋₆alkyl), nitro, cyano, formyl, —C(O)-alkyl (e.g.—C(O)C₁₋₆alkyl, such as acetyl), O—C(O)-alkyl (e.g. —OC(O)C₁₋₆alkyl,such as acetyloxy), benzoyl (wherein benzyl itself may be furthersubstituted e.g., by one or more of C₁₋₆alkyl, halo, hydroxy,hydroxyC₁₋₆alkyl, C₁₋₆alkoxy, C₁₋₆alkoxyC₁₋₆alkyl, C₁₋₆alkoxyC₁₋₆alkoxy,haloC₁₋₆alkyl, haloC₁₋₆alkoxy, cyano, nitro, OC(O)C₁₋₆alkyl, NH₂,NHC₁₋₆alkyl, NHC(O)C₁₋₆alkyl and NC₁₋₆alkylC₁₋₆alkyl), benzoyloxy(wherein benzyl itself may be further substituted e.g., by one or moreof C₁₋₆alkyl, halo, hydroxy, hydroxyC₁₋₆alkyl, C₁₋₆alkoxy,C₁₋₆alkoxyC₁₋₆alkyl, C₁₋₆alkoxyC₁₋₆alkoxy, haloC₁₋₆alkyl,haloC₁₋₆alkoxy, cyano, nitro, OC(O)C₁₋₆alkyl, NH₂, NHC₁₋₆alkyl,NHC(O)C₁₋₆alkyl and NC₁₋₆alkylC₁₋₆alkyl), CO₂H, CO₂alkyl (e.g.CO₂C₁₋₆alkyl such as methyl ester, ethyl ester, propyl ester, butylester), CO₂phenyl (wherein phenyl itself may be further substitutede.g., by one or more of C₁₋₆alkyl, halo, hydroxy, hydroxyC₁₋₆alkyl,C₁₋₆alkoxy, C₁₋₆alkoxyC₁₋₆alkyl, C₁₋₆alkoxyC₁₋₆alkoxy, haloC₁₋₆alkyl,haloC₁₋₆alkoxy, cyano, nitro, OC(O)C₁₋₆alkyl, NH₂, NHC₁₋₆alkyl,NHC(O)C₁₋₆alkyl and NC₁₋₆alkylC₁₋₆alkyl), CO₂benzyl (wherein benzylitself may be further substituted e.g., by one or more of C₁₋₆alkyl,halo, hydroxy, hydroxyC₁₋₆alkyl, C₁₋₆alkoxy, C₁₋₆alkoxyC₁₋₆alkyl,C₁₋₆alkoxyC₁₋₆alkoxy, haloC₁₋₆alkyl, haloC₁₋₆alkoxy, cyano, nitro,OC(O)C₁₋₆alkyl, NH₂, NHC₁₋₆alkyl, NHC(O)C₁₋₆alkyl andNC₁₋₆alkylC₁₋₆alkyl), CONH₂, C(O)NHphenyl (wherein phenyl itself may befurther substituted e.g., by one or more of C₁₋₆alkyl, halo, hydroxy,hydroxyC₁₋₆alkyl, C₁₋₆alkoxy, C₁₋₆alkoxyC₁₋₆alkyl, C₁₋₆alkoxyC₁₋₆alkoxy,haloC₁₋₆alkyl, haloC₁₋₆alkoxy, cyano, nitro, OC(O)C₁₋₆alkyl, NH₂,NHC₁₋₆alkyl, NHC(O)C₁₋₆alkyl and NC₁₋₆alkylC₁₋₆alkyl), C(O)NHbenzyl(wherein benzyl itself may be further substituted e.g., by one or moreof C₁₋₆alkyl, halo, hydroxy, hydroxyC₁₋₆alkyl, C₁₋₆alkoxy,C₁₋₆alkoxyC₁₋₆alkyl, C₁₋₆alkoxyC₁₋₆alkoxy, haloC₁₋₆alkyl,haloC₁₋₆alkoxy, cyano, nitro, OC(O)C₁₋₆alkyl, NH₂, NHC₁₋₆alkyl,NHC(O)C₁₋₆alkyl and NC₁₋₆alkylC₁₋₆alkyl), C(O)NHalkyl (e.g. C(O)NHC₁₋₆alkyl such as methyl amide, ethyl amide, propyl amide, butyl amide)C(O)Ndialkyl (e.g. C(O)N(C₁₋₆alkyl)₂) aminoalkyl (e.g., HNC₁₋₆alkyl-,C₁₋₆alkylHN—C₁₋₆alkyl- and (C₁₋₆alkyl)₂N—C₁₋₆alkyl-), thioalkyl (e.g.,HSC₁₋₆alkyl-), carboxyalkyl (e.g., HO₂CC₁₋₆alkyl-), carboxyesteralkyl(e.g., C₁₋₆alkylO₂CC₁₋₆alkyl-), amidoalkyl (e.g., H₂N(O)CC₁₋₆alkyl-,H(C₁₋₆alkyl)N(O)CC₁₋₆alkyl-), formylalkyl (e.g., OHCC₁₋₆alkyl-),acylalkyl (e.g., C₁₋₆alkyl(O)CC₁₋₆alkyl-), nitroalkyl (e.g.,O₂NC₁₋₆alkyl-), replacement of CH₂ with C═O, replacement of CH₂ withC═S, substitution of 2 adjacent or non-adjacent carbon atoms (e.g. 1,2or 1,3) by one end each of a —O—(CH₂)_(s)—O— or —NR′—(CH₂)_(s)—NR′—group, wherein s is 1 or 2 and each R′ is independently H or C₁₋₆alkyl,and substitution of 2 adjacent or non-adjacent atoms, independentlyselected from C and N, by a C₂₋₅alkylene or C₂₋₅alkenylene group.

The term “sulfoxide”, either alone or in a compound word, refers to agroup —S(O)R wherein R is selected from hydrogen, alkyl, alkenyl,alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl, and aralkyl.Examples of R include hydrogen, C₁₋₂₀alkyl, phenyl and benzyl.

The term “sulfonyl”, either alone or in a compound word, refers to agroup S(O)₂—R, wherein R is selected from hydrogen, alkyl, alkenyl,alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl, acyl, and aralkyl.Examples of R include hydrogen, C₁₋₂₀alkyl, phenyl and benzyl.

The term “sulfonamide”, or “sulfonamyl” of “sulfonamido”, either aloneor in a compound word, refers to a group S(O)₂NRR wherein each R isindependently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl,heteroaryl, heterocyclyl, carbocyclyl, acyl, and aralkyl. Examples of Rinclude hydrogen, C₁₋₂₀alkyl, phenyl and benzyl. In an embodiment atleast one R is hydrogen. In another form, both R are hydrogen.

A “sulfate” group refers to a group —OS(O)₂OR wherein each R isindependently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl,heteroaryl, heterocyclyl, carbocyclyl, acyl, and aralkyl. Examples of Rinclude hydrogen, C₁₋₂₀alkyl, phenyl and benzyl.

The term “sulfonate” refers to a group SO₃R wherein each R isindependently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl,heteroaryl, heterocyclyl, carbocyclyl, acyl, and aralkyl. Examples of Rinclude hydrogen, C₁₋₂₀alkyl, phenyl and benzyl.

The term “thio” is intended to include groups of the formula “—SR”wherein R can be hydrogen (thiol), alkyl, alkenyl, alkynyl, aryl,carbocyclyl, heteroaryl, heterocyclyl, aralkyl, and acyl. Examples of Rinclude hydrogen, C₁₋₂₀alkyl, phenyl and benzyl.

The term, “amino” is used here in its broadest sense as understood inthe art and includes groups of the formula —NR^(A)R^(B) wherein R^(A)and R^(B) may be any independently selected from hydrogen, hydroxyalkyl, alkoxyalkyl, alkenyl, alkynyl, aryl, carbocyclyl, heteroaryl,heterocyclyl, aralkyl, and acyl, each of which may be optionallysubstituted. R^(A) and R^(B), together with the nitrogen to which theyare attached, may also form a monocyclic, or polycyclic ring system e.g.a 3-10 membered ring, particularly, 5-6 and 9-10 membered systems.Examples of “amino” include —NH₂, —NHalkyl (e.g. —NHC₁₋₂₀alkyl),—NHalkoxyalkyl, —NHaryl (e.g. —NHphenyl), —NHaralkyl (e.g. —NHbenzyl),—NHacyl (e.g. —NHC(O)C₁₋₂₀alkyl, —NHC(O)phenyl), —Ndialkyl (wherein eachalkyl, for example C₁₋₂₀, may be the same or different) and 5 or 6membered rings, optionally containing one or more same or differentheteroatoms (e.g. O, N and S). Reference to groups written as“[group]amino” is intended to reflect the nature of the R^(A) and R^(B)groups. For example, “alkylamino” refers to —NR^(A)R^(B) where one ofR^(A) or R^(B) is alkyl. “Dialkylamino” refers to —NR^(A)R^(B) whereR^(A) and R^(B) are each (independently) an alkyl group.

The term “amido” is used here in its broadest sense as understood in theart and includes groups having the formula C(O)NR^(A)R^(B), whereinR^(A) and R^(B) are as defined as above. Examples of amido includeC(O)NH₂, C(O)NHalkyl (e.g. C₁₋₂₀alkyl), C(O)NHaryl (e.g. C(O)NHphenyl),C(O)NHaralkyl (e.g. C(O)NHbenzyl), C(O)NHacyl (e.g.C(O)NHC(O)C₁₋₂₀alkyl, C(O)NHC(O)phenyl), C(O)Nalkylalkyl (wherein eachalkyl, for example C₁₋₂₀, may be the same or different) and 5 or 6membered rings, optionally containing one or more same or differentheteroatoms (e.g. O, N and S).

The term “carboxy ester” is used here in its broadest sense asunderstood in the art and includes groups having the formula CO₂R,wherein R may be selected from groups including alkyl, alkenyl, alkynyl,aryl, carbocyclyl, heteroaryl, heterocyclyl, aralkyl, and acyl.Particular examples of carboxy ester include CO₂C₁₋₂₀alkyl, CO₂aryl(e.g. CO₂phenyl), CO₂aralkyl (e.g. CO₂ benzyl).

In some embodiments, when R¹ is NHCOR₈, A is selected from optionallysubstituted 5-6-membered aryl, heteroaryl, carbocyclyl and heterocyclyl,e.g. phenyl, pyridyl (attached at C2, C3 or C4), pyrazinyl, pyrimidinyl(attached at C2, C4 or C5), pyridazinyl (attached at C3 or C4),s-triazinyl (attached at C2, C4 or C6), as-triazinyl (attached at C3, C5or C6), v-triazinyl (attached at C4, C5 or C6), furanyl (attached at C2or C3), pyrrolyl (attached at C2 or C3), thienyl (attached at C2 or C3),cyclopentyl, cyclohexyl, cyclopentadienyl, cyclohexadienyl, pyranyl,piperidinyl, piperazinyl, morpholinyl, pyrolidinyl and pyrrolinyl. Incertain embodiments A is optionally substituted 5-6-membered aryl oroptionally substituted heteroaryl, particularly optionally substitutedphenyl or optionally substituted pyridyl.

In other embodiments, when R¹ is NHCOR₈, A is selected from optionallysubstituted naphthyl, an optionally substituted 9-10 membered bicyclicheteroaryl group, including N-containing 10-membered groups.

Some particular examples of NHCOR₈ include NHCOC₁₋₆alkyl (e.g. NHCOMe,NHCOEt, NHCOPr), NHCOphenyl and NHCObenzyl. In further examples, whereR¹ is NHCOC₁₋₆alkyl, it is NHCOMe. In other examples it is NHCOC₂₋₆alkyl(e.g. NHCOEt, NHCOPr or NHCOBu).

In other embodiments, when R¹ is NR⁷R⁸, NHCOR₈, N(COR₈)₂, N(COR₇)(COR₈),N═CHOR₈ or N═CHR₈, A is a bicyclic N-containing heteroaryl group such asquinolinyl, isoquinolinyl, cinnolinyl, quinazolinyl, quinoxalinyl,1,8-naphthyridyl, phthalazinyl or pteridinyl, each of which may besubstituted or unsubstituted. The group may be attached via any carbonatom of the ring system. In certain embodiments, the group may beattached via the 2-, 3-, 6- or 7-position as appropriate. In otherembodiments, the group may be attached via the 1-, 4-, 5- or 8-positionas appropriate. Some particular examples contemplated herein are 3- and4-quinolinyl, particularly 3-quinolinyl. In further embodiments, A isunsubstituted.

In some embodiments, when R¹ is NR⁷R⁸, R¹ is NHR⁸, wherein R⁸ isoptionally substituted alkyl or optionally substituted aryl. In otherembodiments when R¹ is NR⁷R⁸, R⁷ and R⁸ together with the N atom towhich they are attached, form a 3-8-membered ring, e.g. together are analkylene group such as —(CH₂)_(q)— where q is 2, 3, 4 or 5.

In yet further embodiments of the invention, A is a bicyclicN-containing heteroaryl group as described above and R¹ is NHCOR₈, suchas NHCOC₁₋₆alkyl. In a particular embodiment, A is 3-quinolinyl and R¹is NHCOMe.

In certain embodiments, when A is quinolinyl, isoquinolinyl, cinnolinyl,quinazolinyl, quinoxalinyl, 1,8-naphthyridyl, phthalazinyl orpteridinyl, particularly quinolinyl, then R¹ is NHR₈, N<(CH₂)_(q),NHCOR₈, N(COR₈)₂, N(COR₇)(COR₈), N═CHOR₈ or N═CHR₈.

In yet other embodiments of the invention, when A is aryl, carbocyclyl,or heterocyclyl then R¹ is NR⁷R⁸, N(COR₈)₂, N(COR₇)(COR₈), N═CHOR₈ orN═CHR₈.

Exemplary optional substituents for A include alkyl, haloalkyl (e.g.mono-, di- or trifluoromethyl, mono-, di-or trichloromethyl and mono-,di-, tri-, tetra, penta- or hexafluoroethyl and mono-, di-, tri-, tetra,penta- or hexachloroethyl), hydroxyalkyl, aminoalkyl, thioalklyl,arylalkyl (e.g. benzyl and phenylethyl), alkoxy, haloalkoxy,hydroxyalkoxyl, aminoalkoxy, alkythio, haloalkythio, hydroxyalkylthio,aminoalkylthio, thioalkythio, amino, C(O)alkyl, OC(O)alkyl, aryl (eg.phenyl), carboxy, carboxy ester (e.g. CO₂alkyl, CO₂aryl), C(O)aryl,OC(O)aryl, nitro, cyano, heteroaryl (e.g. pyridyl), heteroarylalkyl,heterocyclyl, heterocyclylalkyl, hydroxy, thio, methylenedioxy, halo(e.g. Cl, Br) and amido. Where such a substituent is or contains an“alkyl” moiety, it may be C₁₋₁₀alkyl, particularly C₁₋₆alkyl, such asmethyl, ethyl, i-propyl, n-propyl, n-butyl, sec-butyl or t-butyl.

In one embodiment X is O. In another embodiment X is NR′. In yet anotherembodiment X is S. In particular examples X is O. Where X is NR′, someexamples of R′ include hydrogen, C₁₋₁₀alkyl, benzyl, phenylethyl,OC(O)C₁₋₁₀alkyl and OC(O)phenyl.

In one embodiment, Y is hydrogen.

Particular examples of R⁷ and R⁸ include hydrogen, C₁₋₁₀ alkyl, andphenyl wherein C₁₋₁₀ alkyl and phenyl may be optionally substituted.

Some exemplary substituents for R⁷ and R⁸ (including exemplified R⁷ andR⁸ as above) include alkyl, haloalkyl (e.g. mono-, di- ortrifluoromethyl, mono-, di-or trichloromethyl and mono-, di-, tri-,tetra, penta- or hexafluoroethyl and mono-, di-, tri-, tetra, penta- orhexachloroethyl), hydroxyalkyl, aminoalkyl, thioalkyl, arylalkyl (e.g.benzyl and phenylethyl) alkoxy, haloalkoxy, hydroxyalkoxyl, aminoalkoxyalkythio, haloalkythio, hydroxyalkylthio, aminoalkylthio, thioalkythio,amino, C(O)alkyl OC(O)alkyl, aryl (e.g. phenyl) carboxy, carboxy esterC(O)aryl OC(O)aryl, nitro, cyano, heteroaryl (e.g. pyridyl)heteroarylalkyl, heterocyclyl, heterocyclylalkyl, hydroxy, thio,methylenedioxy, halo (e.g. Cl, Br) and amido or together form a5-6-membered ring e.g. (piperidyl, morpholinyl). Where such asubstituent contains an “alkyl” moiety, preferred alkyl are C₁₋₁₀alkyl,particularly C₁₋₆alkyl. Particularly preferred R¹ include NH₂,NHC₁₋₆alkyl, N(C₁₋₆alkyl) (C₁₋₆alkyl) and NHC(O)C₁₋₆alkyl, mostpreferably NH₂.

For R², examples of R⁹ and R¹⁰ include hydrogen, C₁₋₁₀ alkyl, aryl (e.g.phenyl) heteroaryl (e.g. pyridyl). One particularly preferred R² iscyano (CN). Particular examples of R² are CO₂C₁₋₁₀ alkyl, (e.g. CO₂Me,CO₂Et, CO₂Pr, CO₂Bu etc) and amido, e.g. CONH₂.

Examples of suitable R³-R⁶ include hydrogen, chloro, bromo, C₁₋₁₀ alkyl(including cycloalkyl), C₂₋₁₀ alkenyl (including cycloalkenyl), C₂₋₁₀alkynyl (including cycloalkynyl), C₁₋₁₀ alkoxy (e.g. methoxy, ethoxy, n-and i-propoxy and n-, sec- and t-butoxy), phenyl, halophenyl,hydroxyphenyl, aminophenyl, alkylphenyl, hydroxy, NH₂, NHC₁₋₁₀alkyl,NC₁₋₁₀alkylC₁₋₁₀alkyl (wherein each alkyl may be the same or different),nitro, haloalkyl, including trifluoromethyl, trichloromethyl, acyl (e.g.C(O)C₁₋₁₀alkyl), acyloxy (e.g. OC(O)C₁₋₁₀alkyl or OC(O)aryl such asOC(O)phenyl), carboxy ester (e.g. CO₂C₁₋₁₀alkyl and CO₂ phenyl), CO₂H,amido (e.g. CONHC₁₋₁₀alkyl), nitro, cyano, thio, alkylthio (e.g.SC₁₋₁₀alkyl) and 2 of adjacent R³-R⁶ form methylenedioxy. None, one,two, three or four of R³-R⁶ may be hydrogen. In one preferred form, 2 or3 or 4 of R³-R⁶ are hydrogen. In one particular embodiment, R³, R⁴ andR⁶ are all H. In a further embodiment thereof, R³, R⁴ and R⁶ are all Hand R⁵ is hydroxy.

Where any two adjacent R³-R⁶ form a 3-8-membered ring together with theatoms to which they are attached, the ring may be carbocyclic (saturatedor partially unsaturated), heterocyclic, aryl or heteroaryl. In somepreferred embodiments, the ring formed has 5-6-members. Particularlypreferred forms of this embodiment are where R⁵ and R⁶ form a ring.Examples of any two adjacent R³-R⁶ taken together include —(CH₂)_(n)—where n is 1-7, preferably 1-4, particularly 3 or 4, —O—CH₂—O—,O—(CH₂)₂—O —CH═CH₂—CH₂═CH—, —CH₂—NHCH₂—, —(CH₂)₂—NH—CH₂—,—CH₂—NH—(CH₂)₂—, —(CH₂)₂—NH—, —NH—(CH₂)₂—, —NH—CH═CH—, —CH═CH—NH—,—O—CH═CH—, —CH═CH—O—, —S—CH═CH—, —CH═CH—S—, —N═CH—CH═N— O—CH═CH—CH₂—,and —CH₂—CH═CH—O—. Where appropriate, an N atom within such a ring maybe further substituted with alkyl (eg. C₁₋₁₀), aryl (eg. phenyl),arylalkyl (eg. benzyl or phenylethyl), acyl (eg. C(O)C₁₋₁₀alkyl)hydroxyalkyl (eg. C₁₋₁₀), haloalkyl (eg. C₁₋₁₀), carbocyclylalkyl,heteroarylalkyl, heterocyclylalkyl, carbocyclyl, heteroaryl orheterocyclyl.

In yet other embodiments of the invention, X is oxygen, R² is CO₂R⁹(such as CO₂C₁₋₆alkyl, e.g. CO₂Me or CO₂Et), R³, R⁴, R⁶ are allhydrogen, R⁵ is OH and Y is hydrogen.

Some exemplary compounds contemplated by the invention have the formula:

Particular examples thereof are:

-   -   (i) A=3-pyridyl, R═C(═O)CH₃    -   (ii) A=3-quinolinyl, R═H    -   (iii) A=3-quinolinyl, R═C(═O)CH₃

Compounds for use in the invention may be prepared via methods known inthe art of synthetic organic chemistry, see for example WO 02/092594.

Thus, for the preparation of compounds where X is O, an appropriatelysubstituted phenol compound may be reacted with an appropriate aldehydeand malononitrile in the presence of a base such as piperidine orN,N-diisopropylethylamine in accordance with the generalised Scheme 1below:

Alternatively, the aldehyde may be reacted with malononitrile in thepresence of a base, and the resulting arylidene intermediate reactedwith the appropriate phenol.

In an alternative methodology, the appropriately substituted ortho-aroylphenol, aniline or benzenethiol can be reacted with malononitrile (orappropriate cyanoacetate, cyanoacetamide or acylacetonitrile) to accessthe corresponding 4H-chromene, 1,4-dihydroquinoline or 4H-thiochromeneas in Scheme 2 below (where P is H or a protecting group asappropriate).

Suitable dihydroquinoline compounds can also be prepared by reduction ofan appropriately substituted or protected quinoline.

Compounds of formula (I), where R¹ is other than NH₂ may be prepared byconverting the amine to the desired group using chemical transformationsknown in the art, for example as described in Comprehensive OrganicTransformation, A Guide to Functional Group Preparations, R. C. Larock,VCH, 1989 and Advanced Organic Chemistry, Reactions, Mechanisms andStructure, J. March, 3^(rd) Edition, 1985 or 4^(th) Edition, 1992 (theentire contents of which are incorporated herein by reference). Thus,treatment of the amine (NH₂) with a suitable acylating agent such as acarboxylic acid, anhydride or chloride in the presence of an appropriatebase or catalyst provides access to compounds of formula (I) where R¹ isNHCOR⁸. Alkyl and aryl amines can be prepared by treatment of —NH₂ withan appropriate alkyl or aryl halide. Imines may be formed by treatingthe amine group (NH₂) with a suitable carbonyl containing compound suchas an aldehyde or ketone in accordance with art known methods.

Similarly, compounds where R² is other than CN, i.e. carboxylic acid,esters, amides, anhydrides and ketones, may be prepared bytransformations known in the art, see in particular Larock, supra,Chapter 9, pp 963-995. Alternatively, reaction of the appropriatephenol, aldehyde and the appropriate cyanoacetate, cyanoacetamide oracylacetonitrile affords access to compounds where R² is CO₂R⁹,C(O)NR⁹R¹⁰, C(O)R⁹ and C(O)O(O)R⁹.

Compounds where Y is alkyl can be prepared by treating the benzopyranwith DDQ and the subsequent intermediate with CuBr.DMS and analkyllithium compound.

It will be recognised that during the processes for the preparation ofcompounds contemplated by the present invention, it may be necessary ordesirable to protect certain functional groups which may be reactive orsensitive to the reaction or transformation conditions undertaken (e.g.OH (including diols), NH₂, CO₂H, SH, C═O). Suitable protecting groupsfor such functional groups are known in the art and may be used inaccordance with standard practice. As used herein, the term “protectinggroup”, refers to an introduced functionality which temporarily rendersa particular functional group inactive under certain conditions. Suchprotecting groups and methods for their installation and subsequentremoval at an appropriate stage are described in Protective Groups inOrganic Chemistry, 3^(rd) Edition, T. W. Greene and P. G. Wutz, JohnWiley and Sons, 1999, the entire contents of which are incorporatedherein by reference. Exemplary forms of protected groups include:

for amino (NH₂)—carbamates (such as Cbz, Boc, Fmoc), benzylamines,acetamides (e.g. acetamide, trifluoroacetamide);

for carbonyl—acetals, ketals, dioxanes, dithianes, and hydrazones;

for hydroxy—ethers (e.g. alkyl ethers, alkoxylalkyl ethers, allylethers, silyl ethers, benzyl ethers, tetrahydropyranyl ethers),carboxylic acid esters, acetals (e.g. acetonide and benzylidene acetal);

for thio (SH)—ethers (e.g. alkyl ethers, benzyl ethers), esters

for CO₂H—esters (e.g. alkyl esters, benzyl esters).

As used herein, the term “inhibit” or variations thereof when used inrelation to IRAP activity, such as aminopeptidase activity, includesprevention, interruption, disruption, reduction, retardation orotherwise decrease in the rate or extent of IRAP activity, and thusincludes partial inhibition of IRAP activity as well as complete or nearcomplete inhibition.

The level of IRAP inhibitory activity of the compounds disclosed hereincan be initially determined in an in vitro assay, which measures theability of the test compound to inhibit the aminopeptidase activity ofIRAP, by assessing the rate or extent of cleavage or degradation of anIRAP aminopeptidase substrate such as Leu-β-naphthylamide orLeu-4-methylcoumaryl-7-amide. Comparison can then be made to a controlassay, whereby the rate or extent of cleavage is determined in theabsence of the compound. A comparative reduction in the rate or extentof cleavage of the substrate in the presence of the compound can betaken to be a measure of the inhibitory effect of the compound.

Thus, there is also provided a method of determining the IRAP inhibitoryactivity of a compound, comprising:

-   (a) incubating IRAP, an IRAP substrate and a compound as described    herein; and-   (b) assessing the rate or extent of cleavage of the substrate;    wherein a reduction or inhibition in the rate or extent of cleavage    of the substrate, when compared to a control, is indicative of IRAP    inhibitory activity of the compound.

Advantageously, in one or more embodiments of the invention, a compoundof Formula (I), or a pharmaceutically acceptable salt or solvate, mayexhibit selectivity or specificity for IRAP over other enzymes.

In one or more embodiments, compounds of the invention may potentiate,enhance or otherwise increase glucose uptake into neurons.

Disorders and conditions where undesirable or excessive IRAPaminopeptidase activity is implicated or involved may include memory orlearning disorders associated with Alzheimer's disease and other formsof dementia and memory loss (be they age-related, induced through headtrauma, hypoxic damage, surgery, cerebral infarcts or chemical meanssuch as neurotoxins). It should also be appreciated that the compoundsof the present invention may also be useful in enhancing or improvingmemory or learning in normal individuals, i.e. those not suffering fromcognitive pathologies such as those described above.

Memory or learning (e.g. spatial learning) enhancement refers to animprovement in the ability of a subject to memorize or learn informationand can be determined by well established tests. A positive improvementin the “score” or result obtained in such a test compared to ascore/result obtained prior to administration of the compounds is takento be an enhancement in memory or learning as appropriate. In certainembodiments of the invention, the improvement can be expressed as a %(score after administration of compound/score prior to administration ofcompound) and may represent an improvement of at least about 10%, 20%,25%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 150% or 200%.

A number of well known and established tests exist for laboratoryanimals and rats and mice can be tested using these, which include theBarnes Maze paradigm (Greferath et al., 2000), Barnes Circular Maze test(Lee et al., 2004) or modifications thereof, the Y maze test, or passiveavoidance test. Suitable examples of these are briefly outlined below.

1. Barnes Maze

Normal male Sprague-Dawley rats are implanted with cannulas in thelateral ventricles and allowed to recover for at least three days. Forthe Barnes Circular Maze test, the maze comprises a raised rotatablewhite circular platform of diameter 1.2 m, with 18 evenly spaced holesin the periphery (diameter 0.09 m). An escape tunnel comprising a blackbox of internal diameter of 0.16 m width, 0.29 m length and 0.09 m depthis positioned immediately beneath a peripheral hole. Visual cues areplaced at various positions around the maze.

For each trial, the animal is placed on the maze platform under thestarting chamber, which is a cylindrical chamber located in the centreof the platform, and left for 20 s. Following the twenty secondsdisorientation period the chamber is raised. The animals are thenallowed 240 s in which to find and utilise the escape tunnel. Each ratreceives three consecutive trials per day over ten days. On the firstday of the testing period, each rat is placed directly into the escapetunnel for a 2 min familiarisation period. The rat is then replaced intoits cage for approximately one minute, after which the animal isinjected with either the test compound or artificial cerebrospinal fluidand then replaced into its cage for a further 5 min. Three consecutivetrials are then carried out, with a recovery period of 2 min betweeneach trial in its home cage. On subsequent days (days 2 to 8), thefamiliarisation period prior to the three trials is eliminated from theprotocol.

Animals can be administered the compounds of the inventionintracerebroventricularly (icv) via a chronic indwelling cannula. Thesecompounds are given 5 mins before the first trial on the first day oftesting.

2. Y Maze

The Y-maze test is another behavioural paradigm which measures spatialmemory performance, and exploits the natural instinct of rodents toexplore novel environments.

The Y maze consists of three identical alleys (30 cm in length, 10 cm inwidth and 17 cm in height) with the three arms separated by 120° angles.To minimize stress, the maze is located in a sound-attenuated room underdim illumination, with the floor of the maze covered with sawdust. Aftereach trial, the sawdust is mixed to eliminate olfactory cues. Forspatial orientation, visual cues are placed on the walls of the testingroom.

The test consists of two trials, separated by a time interval known asthe intertrial interval. During the acquisition trial, the animals areplaced at the distal end of one arm, their heads pointing away from thecentre of the maze. The animals are allowed to visit only two accessiblearms of the maze for 3 minutes. At the end of the acquisition trial,animals are replaced in their cages for the intertrial interval. Duringthe retention trial, the animals have access to all three arms for 5minutes. The first arm entered (novel vs familiar), the number ofentries and duration of time spent in the novel arm is documented.

A shorter intertrial interval (2 hours) separating the acquisition phasefrom the retention phase enables amnesiant effects to be detected.Control animals still remember the location of the novel arm and willpreferentially spend more time (45-50% of time) in that arm. A longerintertrial interval (e.g. 6 hours) results in the animals notremembering the location of the novel arm and hence spending equalamount of time in all three arms.

Animals are surgically implanted with an infusion cannula in the dorsalthird ventricle. Each animal is tested twice, and the intertrialinterval of greater than 6 h can be adopted to test for memory-enhancingproperties of the test compounds. Animals are administered the compoundsintracerebroventricularly via a chronic indwelling cannula. Thesecompounds are given 5 mins before the first acquisition trial. Theanimals are then returned to their home cages for at least 6 hours andthen tested again. The time spent in the novel arm will be a measure ofthe memory enhancing properties of the test compound.

3. Passive Avoidance

Passive avoidance trials can be used to test the effect of IRAPinhibitors on aversive conditioning behaviour in amnesic animals. Thepassive avoidance task involves aversive conditioning behaviour tomeasure facilitation of memory retention and retrieval. The testing canbe carried out in an apparatus that consists of a light and a darkcompartment separated by a guillotine door. The floor of the darkcompartment contains an electrified grid. The passive avoidance task isdivided into two trials separated by a 24-48 h inter-trial interval.During the first trial, known as the acquisition trial, the animal isplaced in the lit compartment and the guillotine door is closed once theanimal enters the dark compartment. Inside the dark chamber, the animalreceives a low-level electric shock (0.5 mA for 2 s) via the grid floor.The animal is then returned to its home cage for 24 h or 48 h beforebeing tested. The latency periods to re-enter the dark compartment aretaken as a measure of the ability of the animals to remember theaversive stimuli.

Animals are surgically implanted with an infusion cannula in the dorsalthird ventricle. Each animal is tested twice, and the intertrialinterval of 24 h and 48 h can be adopted to test for memory-enhancingproperties of the test compounds. Animals are administered the compoundsintracerebroventricularly via a chronic indwelling cannula. Thesecompounds are given 5 mins before the acquisition trial. The animals arethen returned to their home cages for 24 h or 48 h and then testedagain. The latency in entering the dark chamber will be a measure of thememory-enhancing property of the test compound.

4. Age-Induced Memory Deficit Model

Spatial learning impairment in aged rats is well documented and thisdeficit can be detected in the Barnes maze paradigm (Greferath et al.,2000). The effect of IRAP inhibitors on aged-induced learning deficitscan be tested in the Barnes maze paradigm.

For drug treatment, the animals are implanted with Alzet minipumps(secured subcutaneously in the neck region) which delivers the testcompounds chronically into the cerebral ventricles.

5. Animal Model of Alzheimer's Dementia

The effects of the IRAP inhibitors can be tested in a mouse model ofAlzheimer's disease, the Tg2576 transgenic mouse (with the Swedishmutation Lys-670-Asn; Met-671-Leu). This mouse model of Alzheimer'sdisease is commercially available from Taconic Biotechnology, and themice have demonstrated deficits in spatial learning (water maze) andworking memory (spontaneous alternation Y maze).

Memory and learning can be tested in humans by any one of a number ofwell established neuropsychological tests such as California VerbalLearning Test, Wechsler Memory Scale-III, Hopkins Verbal LearningTest—Revised™, Rey Auditory Verbal Learning Test, and Rey-OsterriethComplex Figure Design Test.

Subjects to be treated by the compounds and methods of the inventioninclude mammalian subjects: humans, non-primates, livestock animals(including cows, horses, sheep, pigs and goats), companion animals(including dogs, cats, rabbits, guinea pigs), and captive wild animals.Laboratory animals such as rabbits, mice, rats, guinea pigs and hamstersare also contemplated as they may provide a convenient test system.Non-mammalian species such as birds, amphibians and fish may also becontemplated in certain embodiments of the invention. In particularembodiments, the subject is a human subject.

The compounds of the invention are administered to the subject in anIRAP inhibiting, or otherwise treatment effective amount. An IRAPinhibiting amount is an amount which will at least partially interactwith IRAP or disrupt IRAP activity. IRAP activity as used hereinincludes IRAP functional interaction with endogenous ligands,particularly where the functional interaction directly or indirectlypromotes memory and/or learning loss. A treatment effective amount isintended to include an amount which, when administered according to thedesired dosing regimen, results in a measurable improvement orenhancement in memory or learning, or at least partially attains thedesired therapeutic or prophylactic effect of one or more of:alleviating, eliminating or reducing the frequency of one or more of thesymptoms of, preventing or delaying the onset of, inhibiting theprogression of, or halting or reversing, partially or altogether, theonset or progression of the particular disorder or condition beingtreated.

Suitable dosage amounts and dosing regimens can be determined by theattending physician and may depend on the particular condition beingtreated, the severity of the condition as well as the general age,health and weight of the subject.

The active ingredient may be administered in a single dose or a seriesof doses. While it is possible for the active ingredient to beadministered alone, it is preferable to present it as a composition,preferably as a pharmaceutical composition, with one or morepharmaceutically acceptable adjuvants. Thus, the present invention alsorelates to the use of a compound of formula (I) or a pharmaceuticallyacceptable salt or solvate thereof in the manufacture of a medicamentfor inhibiting IRAP activity in a subject.

The formulation of such compositions is well known to those skilled inthe art, see for example, Remington's Pharmaceutical Sciences, 18^(th)Edition, Mack Publishing, 1990. The composition may contain any suitablecarriers, diluents or excipients. These include all conventionalsolvents, dispersion media, fillers, solid carriers, coatings,antifungal and antibacterial agents, dermal penetration agents,surfactants, isotonic and absorption agents and the like. It will beunderstood that the compositions of the invention may also include othersupplementary physiologically active agents.

The carrier must be pharmaceutically acceptable in the sense of beingcompatible with the other ingredients of the composition and notinjurious to the subject. Compositions include those suitable for oral,rectal, nasal, topical (including dermal, buccal and sublingual),vaginal or parental (including subcutaneous, intramuscular, intravenous,intracerebroventricular and intradermal) administration. Thecompositions may conveniently be presented in unit dosage form and maybe prepared by any methods well known in the art of pharmacy. Suchmethods include the step of bringing into association the activeingredient with the carrier which constitutes one or more accessoryingredients. In general, the compositions are prepared by uniformly andintimately bringing into association the active ingredient with liquidcarriers or finely divided solid carriers or both, and then if necessaryshaping the product.

Compositions of the present invention suitable for oral administrationmay be presented as discrete units such as capsules, sachets or tabletseach containing a predetermined amount of the active ingredient; as apowder or granules; as a solution or a suspension in an aqueous ornon-aqueous liquid; or as an oil-in-water liquid emulsion or awater-in-oil liquid emulsion.

A tablet may be made by compression or moulding, optionally with one ormore accessory ingredients. Compressed tablets may be prepared bycompressing in a suitable machine the active ingredient in afree-flowing form such as a powder or granules, optionally mixed with abinder (e.g. inert diluent), preservative disintegrant (e.g. sodiumstarch glycolate, cross-linked polyvinyl pyrrolidone, cross-linkedsodium carboxymethyl cellulose) surface-active or dispersing agent.Moulded tablets may be made by moulding in a suitable machine a mixtureof the powdered compound moistened with an inert liquid diluent. Thetablets may optionally be coated or scored and may be formulated so asto provide slow or controlled release of the active ingredient thereinusing, for example, hydroxypropylmethyl cellulose in varying proportionsto provide the desired release profile. Tablets may optionally beprovided with an enteric coating, to provide release in parts of the gutother than the stomach.

Compositions suitable for topical administration in the mouth includelozenges comprising the active ingredient in a flavoured base, usuallysucrose and acacia or tragacanth gum; pastilles comprising the activeingredient in an inert basis such as gelatin and glycerin, or sucroseand acacia gum; and mouthwashes comprising the active ingredient in asuitable liquid carrier.

Compositions suitable for topical administration to the skin maycomprise the compounds dissolved or suspended in any suitable carrier orbase and may be in the form of lotions, gel, creams, pastes, ointmentsand the like. Suitable carriers include mineral oil, propylene glycol,polyoxyethylene, polyoxypropylene, emulsifying wax, sorbitanmonostearate, polysorbate 60, cetyl esters wax, cetearyl alcohol,2-octyldodecanol, benzyl alcohol and water. Transdermal patches may alsobe used to administer the compounds of the invention.

Compositions for rectal administration may be presented as a suppositorywith a suitable base comprising, for example, cocoa butter, glycerin,gelatin or polyethylene glycol.

Compositions suitable for vaginal administration may be presented aspessaries, tampons, creams, gels, pastes, foams or spray formulationscontaining in addition to the active ingredient such carriers as areknown in the art to be appropriate.

Compositions suitable for parenteral administration (e.g. subcutaneous,intramuscular, intravenous or intracerebroventricular) may includeaqueous and non-aqueous isotonic sterile injection solutions which maycontain anti-oxidants, buffers, bactericides and solutes which renderthe composition isotonic with the blood of the intended recipient; andaqueous and non-aqueous sterile suspensions which may include suspendingagents and thickening agents. The compositions may be presented inunit-dose or multi-dose sealed containers, for example, ampoules andvials, and may be stored in a freeze-dried (lyophilised) conditionrequiring only the addition of the sterile liquid carrier, for examplewater for injections, immediately prior to use. Extemporaneous injectionsolutions and suspensions may be prepared from sterile powders, granulesand tablets of the kind previously described.

Preferred unit dosage compositions are those containing a daily dose orunit, daily sub-dose, as herein above described, or an appropriatefraction thereof, of the active ingredient.

It should be understood that in addition to the active ingredientsparticularly mentioned above, the compositions of this invention mayinclude other agents conventional in the art having regard to the typeof composition in question, for example, those suitable for oraladministration may include such further agents as binders, sweeteners,thickeners, flavouring agents disintegrating agents, coating agents,preservatives, lubricants and/or time delay agents. Suitable sweetenersinclude sucrose, lactose, glucose, aspartame or saccharine. Suitabledisintegrating agents include corn starch, methylcellulose,polyvinylpyrrolidone, xanthan gum, bentonite, alginic acid or agar.Suitable flavouring agents include peppermint oil, oil of wintergreen,cherry, orange or raspberry flavouring. Suitable coating agents includepolymers or copolymers of acrylic acid and/or methacrylic acid and/ortheir esters, waxes, fatty alcohols, zein, shellac or gluten. Suitablepreservatives include sodium benzoate, vitamin E, alpha-tocopherol,ascorbic acid, methyl paraben, propyl paraben or sodium bisulphite.Suitable lubricants include magnesium stearate, stearic acid, sodiumoleate, sodium chloride or talc. Suitable time delay agents includeglyceryl monostearate or glyceryl distearate.

It will be understood that the compounds contemplated herein may bepresented as prodrugs of formula (I). Any compound that is a prodrug ofa compound of formula (I) is within the scope and spirit of theinvention. The term “prodrug” is used in its broadest sense andencompasses those derivatives that are converted in vivo, eitherenzymatically or hydrolytically, to the compounds of the invention. Suchderivatives would readily occur to those skilled in the art, andinclude, for example, compounds where a free thiol or hydroxy group isconverted into an ester, such as an acetate, or thioester or where afree amino group is converted into an amide. Procedures for acylatingthe compounds of the invention, for example to prepare ester and amideprodrugs, are well known in the art and may include treatment of thecompound with an appropriate carboxylic acid, anhydride or chloride inthe presence of a suitable catalyst or base. Esters of carboxylic acid(carboxy) groups are also contemplated. Suitable esters C₁₋₆alkylesters; C₁₋₆alkoxymethyl esters, for example methoxymethyl orethoxymethyl; C₁₋₆alkanoyloxymethyl esters, for example,pivaloyloxymethyl; phthalidyl esters; C₃₋₈cycloalkoxycarbonylC₁₋₆alkylesters, for example, 1-cyclohexylcarbonyloxyethyl;1,3-dioxolen-2-onylmethyl esters, for example,5-methyl-1,3-dioxolen-2-onylmethyl; and C₁₋₆alkoxycarbonyloxyethylesters, for example, 1-methoxycarbonyloxyethyl. Prodrugs of aminofunctional groups include amides (see, for example, Adv. BioSci., 1979,20, 369, Kyncl, J. et al), enamines (see, for example, J. Pharm. Sci.,1971, 60, 1810, Caldwell, H. et al), Schiff bases (see, for example,U.S. Pat. No. 2,923,661 and Antimicrob. Agents Chemother., 1981, 19,1004, Smyth, R. et al), oxazolidines (see, for example, J. Pharm. Sci,1983, 72, 1294, Johansen, M. et al), Mannich bases (see, for example, J.Pharm. Sci. 1980, 69, 44, Bundgaard, H. et al and J. Am. Chem. Soc.,1959, 81, 1198, Gottstein, W. et al), hydroxymethyl derivatives (see,for example, J. Pharm. Sci, 1981, 70, 855, Bansal, P. et al) andN-(acyloxy)alkyl derivatives and carbamates (see, for example, J. Med.Chem., 1980, 23, 469, Bodor, N. et al, J. Med. Chem., 1984, 27, 1037,Firestone, R. et al, J. Med. Chem., 1967, 10, 960, Kreiger, M. et al,U.S. Pat. No. 5,684,018 and J. Med. Chem., 1988, 31, 318-322, Alexander,J. et al). Other conventional procedures for the selection andpreparation of suitable prodrugs are known in the art and are described,for example, in WO 00/23419; Design of Prodrugs, H. Bundgaard, Ed.,Elsevier Science Publishers, 1985; Methods in Enzymology, 42: 309-396,K. Widder, Ed, Academic Press, 1985; A Textbook of Drug Design andDevelopment, Krogsgaard-Larsen and H. Bundgaard, Eds, Chapter 5, p113-191 (1991); Advanced Drug Delivery Reviews, 8; 1-38 (1992); Journalof Pharmaceutical Sciences, 77;285 (1988), H. Bundgaard, et al; ChemPharm Bull, 32692 (1984), N. Kakeya et al and The Organic Chemistry ofDrug Desig and Drug Action, Chapter 8, pp 352-401, Academic press, Inc.,1992.

Suitable pharmaceutically acceptable salts of compounds of formula (I)include, but are not limited to salts of pharmaceutically acceptableinorganic acids such as hydrochloric, sulphuric, phosphoric nitric,carbonic, boric, sulfamic, and hydrobromic acids, or salts ofpharmaceutically acceptable organic acids such as acetic, propionic,butyric, tartaric, maleic, hydroxymaleic, fumaric, maleic, citric,lactic, mucic, gluconic, benzoic, succinic, oxalic, phenylacetic,methanesulphonic, toluenesulphonic, benezenesulphonic, salicyclicsulphanilic, aspartic, glutamic, edetic, stearic, palmitic, oleic,lauric, pantothenic, tannic, ascorbic, fendizoic,4-4′-methylenebis-3-hydroxy-2-naphthoic acid,o-(p-hydroxybenzoyl)benzoic,4′-4″-dihydroxytriphenylmethane-2-carboxylic acid and valeric acids.Base salts include, but are not limited to, those formed withpharmaceutically acceptable cations, such as sodium, potassium, lithium,calcium, magnesium, ammonium and alkylammonium. Basicnitrogen-containing groups may be quaternised with such agents as loweralkyl halide, such as methyl, ethyl, propyl, and butyl chlorides,bromides and iodides or dialkyl sulfates such as dimethyl and diethylsulfate.

The compounds of the invention may be in crystalline form either as thefree compounds or as solvates and it is intended that both forms arewithin the scope of the present invention. The term “solvate” refers toa complex or aggregate formed by one or more molecules of a solute, i.e.compounds contemplated by the invention, and one or more molecules of asolvent. Suitable solvents are well understood in the art and includefor example, of water, i.e. to form hydrates, and common organicsolvents such as alcohols (methanol, ethanol, isopropanol) and aceticacid. Methods of solvation are generally known within the art, forexample, recrystallization from an appropriate solvent.

Tautomeric forms of compounds described herein, such as keto-enoltautomers, are also contemplated to be part of the invention whereappropriate.

It will also be recognised that certain compounds of formula (I) maypossess asymmetric centres and are therefore capable of existing in morethan one stereoisomeric form, such as enantiomers and diastereomers. Theinvention thus also relates to optically active compounds and compoundsin substantially pure isomeric form at one or more asymmetric centres,e.g., diastereoisomers and enantiomers having greater than about 90% ee,such as about 95% or 97% ee or greater than 99% ee, as well as mixtures,including racemic mixtures, thereof. Such isomers may be prepared byasymmetric synthesis, for example using chiral intermediates, enzymes,or mixtures may be resolved by conventional methods, e.g.,chromatography, recrystallization, or use of a resolving agent.

The compounds of the invention may also be used to treat non-humansubjects and may therefore be presented as veterinary compositions.These may be prepared by any suitable means known in the art. Examplesof such compositions include those adapted for:

-   (a) oral administration, external application (e.g. drenches    including aqueous and non-aqueous solutions or suspensions),    tablets, boluses, powders, granules, pellets for admixture with    feedstuffs, pastes for application to the tongue;-   (b) parenteral administration, e.g. subcutaneous, intramuscular,    intravenous or intracerebroventricular injection as a sterile    solution or suspension;-   (c) topical application e.g. creams, ointments, gels, lotions etc.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It is to be understood that the inventionincludes all such variations and modifications which fall within thespirit and scope. The invention also includes all of the steps,features, compositions and compounds referred to or indicated in thisspecification, individually or collectively, and any and allcombinations of any two or more of said steps or features.

The following examples are provided for the purpose of illustratingcertain embodiments of the invention and are not intended to limit thegeneralities hereinbefore described.

EXAMPLES Example 1

Four compounds (1-4) were prepared and tested for IRAP inhibitoryactivity and compared against the most potent exemplified compound of WO2006/026832.

Preparation of Comparative Compound 1 from WO 2006/026832

-   (i) 3-Pyridine carboxaldehyde (2.2 g) and ethylcyanoacetate (2.3 g)    were heated at reflux in toluene together with acetic acid (100 μl)    and piperidine (40 μl). Nitrogen was blown over the surface to help    remove water. A precipitate formed on cooling and standing, with the    addition of pet. spirit. A cream-coloured crystalline solid (3.0 g)    was collected.-   (ii) (Reference: Org. Prep and Proc., 1999, 31, 305)    -   The ethylacrylate ester product of (i) above (1.0 g) was        dissolved, together with resorcinol (0.55 g) in 15 ml ethanol at        80° C. Piperidine (5 drops) was added to the solution and the        mixture heated at reflux for 4 hours. A white solid was        collected and the title compound separated from the dimeric        product to afford 40 mg of the desired compound.    -   The desired product was obtained in 48% yield, free of dimeric        product when 1.5 equivalents of resorcinol was used on a 4.9        mmol scale.

Compound 1 Ethyl2-amino-7-hydroxy-4-quinolin-4-yl-4H-chromene-3-carboxylate

-   (i) Ethyl 2-cyano-3-quinolinyl-4-ylacrylate was obtained in a    similar manner to that described above by reaction of    4-quinolinecarboxaldehyde and ethyl cyanoacetate. The product    precipitated from the reaction mixture and was isolated by    filtration (1.432 g, 61%).-   (ii)

-    A mixture of resorcinol (126 mg, 1.14 mmol) and ethyl    2-cyano-3-quinolin-4-ylacrylate (254 mg, 1.01 mmol) was suspended in    absolute ethanol (3.0 mL). Piperidine (20 μL) was added and the    mixture heated at reflux for 3 h. A precipitate formed on cooling.    The mixture was filtered. The residue was dissolved in a mixture of    ethyl acetate (20 mL) and ethanol (5 mL). Silica gel 60 (0.9 g) was    added and the mixture evaporated to dryness. Purified by flash    chromatography over silica gel 60, 40-63 μm (eluent: 75% ethyl    acetate/petroleum spirits (8×20 mL fractions), packing height: 18    cm, column diameter: 1 cm). The fractions containing the major band    (R_(f) 0.43, eluent: 75% ethyl acetate/petroleum spirits, fractions    3-5) were combined and evaporated to dryness. The residue was dried    in a vacuum oven (80° C., 200 mbar) for 6 h to give the title    compound (115 mg, 32%) as a yellow powder.

HPLC (214 nm) t_(R)=6.02 min (97%).

¹H NMR (400 MHz, DMSO-d₆) δ 0.61 (t, J=7.2 Hz, 3H), 3.64-3.79 (m, 2H),5.78 (s, 1H), 6.37 (dd, J=8.4, 2.4 Hz, 1H), 6.48 (d, J=2.4 Hz, 1H), 6.82(d, J=8.4 Hz, 1H), 7.19 (d, J=4.4 Hz, 1H), 7.64-7.80 (m, 4H), 8.00 (dd,J=8.4, 1.2 Hz, 1H), 8.64 (br d, J=8.4 Hz, 1H), 8.74 (d, J=4.8 Hz, 1H),9.67 (s, 1H).

Compound 2 Ethyl2-(acetylamino)-7-hydroxy-4-pyridin-3-yl-4H-chromene-3-carboxylate

Ethyl7-(acetyloxy)-2-(diacetylamino)-4-pyridin-3-yl-4H-chromene-3-carboxylate(6.989 g, 15.9 mmol) was dissolved in absolute ethanol (50 mL).Hydrazine hydrate (950 μL, 19.5 mmol) was added and the mixture stirredat room temperature for 6 h. The reaction mixture was evaporated todryness to give an orange solid. The residue was dissolved in a mixtureof ethyl acetate (200 mL) and ethanol (50 mL). Silica gel 60 (35 g) wasadded and the mixture evaporated to dryness. Purified by flashchromatography over silica gel 60, 40-63 μm (eluent: 75% ethylacetate/petroleum spirits (54×100 mL fractions), packing height: 15 cm,column diameter: 5 cm). The fractions containing the major band (R_(f)0.26, eluent: 75% ethyl acetate/petroleum spirits, fractions 15-53) werecombined and evaporated to dryness to give the title compound (3.307 g,59% yield) as a pale yellow powder.

HPLC (214 nm) t_(R)=5.05 min (99%).

¹H NMR (400 MHz, DMSO-d₆) δ 1.09 (t, J=7.0 Hz, 3H), 2.08 (s, 3H), 3.99(q, J=6.9 Hz, 2H), 4.99 (s, 1H), 6.47 (d, J=2.4 Hz, 1H), 6.55 (dd,J=8.4, 2.4 Hz, 1H), 7.10 (d, J=8.4 Hz, 1H), 7.27 (dd, J=7.8, 4.6 Hz,1H), 7.57-7.62 (m, 1H), 8.36 (dd, J=4.8, 1.6 Hz, 1H), 8.54 (d, J=2.0 Hz,1H), 9.75 (br s, 1H), 10.35 (br s, 1H).

LC/MS t_(R)=5.43 min (355.5 [M+H]⁺).

MP 216-218° C.

Compound 3 Ethyl2-amino-7-hydroxy-4-quinolin-3-yl-4H-chromene-3-carboxylate

-   (i) Ethyl 2-cyano-3-quinolin-3-ylacrylate was obtained in a similar    manner to that described above by reaction of    3-quinolinecarboxaldehyde and ethyl cyanoacetate. The product    precipitated from the reaction mixture and was isolated by    filtration (1.023 g, 92%).-   (ii)

-    A mixture of resorcinol (512 mg, 4.65 mmol), ethyl    2-cyano-3-quinolin-3-ylacrylate (1.003 g, 3.98 mmol), piperidine (80    μL, 0.81 mmol) and absolute ethanol (12 mL) was heated at reflux for    3 h. A precipitate formed on cooling. Water (36 mL) was added and    the mixture filtered. The residue was washed with water (2×30 mL),    dried in a vacuum desiccator over silica gel, washed with ethyl    acetate (5 mL) and dried under high vacuum (180° C., 0.5 mbar) for    90 min to give an orange powder (794 mg, 55% yield). A portion of    this product (596 mg) was suspended in ethanol (20 mL). Silica gel    60 (3.1 g) was added and the mixture evaporated to dryness. Purified    by flash chromatography over silica gel 60, 40-63 μm (eluent: 75%    ethyl acetate/petroleum spirits (19×40 mL fractions), ethyl acetate    (16×40 mL fractions), ethanol (7×40 mL fractions), packing height:    15 cm, column diameter: 2.5 cm). The pale yellow fractions    containing the major band (R_(f) 0.33, eluent: 75% ethyl    acetate/petroleum spirits, fractions 4-37) were combined and    evaporated to dryness. The residue was dried under high vacuum (150°    C., 0.75 mbar) for 15 min to give the title compound (282 mg, 47%    recovery) as a yellow powder.

HPLC (214 nm) t_(R)=5.86 min (92%).

¹H NMR (400 MHz, DMSO-d₆) δ 1.00 (t, J=7.0 Hz, 3H), 3.92 (q, J=7.1 Hz,2H), 5.05 (s, 1H), 6.45-6.52 (m, 2H), 7.02 (d, J=8.8 Hz, 1H), 7.54 (t,J=7.4 Hz, 1H), 7.63-7.78 (m, 3H), 7.93 (t, J=8.4 Hz, 2H), 7.98 (d, J=2.0Hz, 1H), 8.75 (d, J=2.0 Hz, 1H), 9.70 (s, 1H).

LC/MS t_(R)=6.25 (363.4 [M+H]⁺) min.

MP 229-231° C.

Compound 4 Ethyl2-(acetylamino)-7-hydroxy-4-quinolin-3-yl-4H-chromene-3-carboxylate

Ethyl7-(acetyloxy)-2-(diacetylamino)-4-quinolin-3-yl-4H-chromene-3-carboxylate(268 mg, 0.55 mmol) was dissolved in absolute ethanol (1.7 mL).Hydrazine hydrate (35 μL, 0.72 mmol) was added and the mixture stirredat room temperature for 1 h. The reaction mixture was evaporated todryness. ¹H NMR analysis showed incomplete conversion of the startingmaterial. The product was suspended in absolute ethanol (1.7 mL) andhydrazine hydrate (35 μL, 0.72 mmol) added. The mixture was stirred atroom temperature for 2 h. The mixture was filtered. The residue waswashed with ethanol (1.0 mL) and ethyl acetate (2.0 mL). The residue wasdissolved in boiling ethanol (16 mL) and the volume reduced to half byheating under a stream of nitrogen. The mixture was cooled to 4° C. andfiltered. The residue was dried at the pump to give the title compound(65 mg, 29% yield) as pale yellow needles.

HPLC (214 nm) t_(R)=5.84 min (98.5%).

NMR (400 MHz, DMSO-d₆) δ 1.07 (t, J=7.2 Hz, 3H), 2.11 (s, 3H), 3.98 (q,J=7.1 Hz, 2H), 5.20 (s, 1H), 6.51 (d, J=2.0 Hz, 1H), 6.55 (dd, J=8.4,2.4 Hz, 1H), 7.16 (d, J=8.4 Hz, 1H), 7.57 (t, J=7.4 Hz, 1H), 7.69 (t,J=7.6 Hz, 1H), 7.89 (d, J=8.0 Hz, 1H), 7.96 (d, J=8.0 Hz, 1H), 8.13 (d,J=2.0 Hz, 1H), 8.89 (d, J=2.0 Hz, 1H), 9.78 (br s, 1H), 10.41 (br s,1H).

LC/MS t_(R)=6.27 min (405.4 [M+H]⁺).

MP 248-251° C.

Example 2

An in vitro enzymatic assay was used to initially assess IRAP inhibitoryactivity.

IRAP Enzymatic Assay

Crude membranes were prepared from HEK 293T cells transfected with IRAPor empty vector, then solubilized in buffer consisting of 50 mMTris-HCl, 1% Triton X-100, pH 7.4 at 4° C. under agitation over 5 h.After solubilization, the membranes were pelleted by centrifugation at23,100 g for 15 min at 4° C., and the supernatant was reserved as thesource of IRAP activity. The enzymatic activities of MAP were determinedby the hydrolysis of the synthetic substrate Leu-MCA (Sigma-Aldrich,Missouri, USA) monitored by the release of a fluorogenic product, MCA,at excitation and emission wavelengths of 380 and 440 nm, respectively.Assays were performed in 96-well plates; each well contains between0.2-10 μg solubilized membrane protein, a range of concentration ofsubstrate in a final volume of 100 μL 50 mM Tris-HCl buffer (pH 7.4).Non-specific hydrolysis of the substrate was corrected by subtractingthe emission from incubations with membranes transfected with emptyvector. Reactions proceeded at 37° C. for 30 min within a thermostattedFLEX station fluorescence microplate reader (Molecular Devices,Sunnyvale, Calif.). The kinetic parameters (K_(m) and V) were determinedby non-linear fitting of the Michaelis-Menten equation (GraphPad Prism,GraphPad Software Inc., CA, USA); final concentrations of Leu-MCA of15.6 μM-1 mM. Inhibitor constants (K_(i)) for the competitive inhibitorswere calculated from the relationship IC₅₀=K_(i) (1+[S]/K_(m)), whereIC₅₀ values were determined over a range of inhibitor concentrations(10⁻⁹ to 10⁻⁴ M). K_(m) values of IRAP for Leu-MCA were determined fromthe kinetic studies. Binding affinities of the compounds to IRAP wereexamined by monitoring the inhibition of the hydrolysis of Leu-MCA inthe presence of increasing concentrations of the compounds (10⁻⁸ to 10⁻³M). All data obtained were from at least three separate experimentsperformed in duplicate.

The results are depicted in Table 2-1.

Compounds K₁ (uM) IC₅₀ Structures 1 0.9 1.5 μM

2 0.48 0.79 μM

3 0.36 0.6 μM

4 0.02 40 nM

Compound 1 from WO 2006/026832 (Comparative) 2.0 3 μM

In order to see whether the compounds are selective or specific forIRAP, the inhibitory activities of Compounds 2-4 for otherzinc-dependent metallopeptidases were determined in 96-well microtiterplates with absorbance monitored on a Wallac Victor 3 spectrophotometer.

Glucose-6-phosphate dehydrogenase and hexokinase activity.Glucose-6-phosphate dehydrogenase and hexokinase activity in the absenceand presence of the compounds was determined in a fluorimetric assay.Ten mM Tris MgCl₂ buffer (total volume of 200 ml) containingglucose-6-phosphate dehydrogenase, 0.3 M ATP, 30 mM NADP+ was added to96 well microtitre plate together with 20 μl of compound, a reading atexcitation 350 nm and emission 510 nm was taken followed by the additionof hexokinase and another reading.

Leukotriene A4 hydrolase assay. Recombinant human LTA4H (CaymanChemicals Michigan USA) (1-20 μg) was incubated at room temperature withalanine-p-nitroanilide as substrate in 50 mM Tris-HCl buffer, pH 8.0,containing 100 mM KCl with or without increasing concentrations of aninhibitor. The absorbance at 405 nm was measured at 10 min intervals.

Aminopeptidase N assay. 5 mU of aminopeptidase M (Sigma Aldrich) wasincubated with 100 μM of substrate alanine-β-naphthylamide (SigmaAldrich) in Tris buffered saline (50 mM Tris-HCl, 150 mM NaCl pH 7.5) at25° C. IRAP inhibitors (1-10 μM) were added after 1 minute andfluorescence at 405 nm was followed.

Angiotensin converting enzyme assay. The enzyme (final concentration0.02 pmol/100 μL) was incubated with 200 μL of assay solution thatincluded 5 mmol/L HHL in 100 mmol/L potassium buffer (pH 8.3) thatcontained 300 mmol/L NaCl and 10⁻⁴ mol/L ZnSO₄ for 3 hours at 37° C. Theenzymatic reaction was stopped by the addition of 1.5 mL of 0.28N NaOH,100 μL of o-phthaldialdehyde (20 mg/mL) in methanol was added and thefluorescent reaction stopped by the addition of 200 μL of 3N HCl. Theproduct, L-His-Leu, was measured fluorometrically (360 nm excitation and500 nm emission).

Limited inhibition of control enzymes was observed. The results aredepicted in Table 2-2 and are expressed as % inhibition of the catalyticactivity of the enzyme at the given concentration.

TABLE 2-2 Compound 2 Compound 3 Compound 4 100 100 100 10 μM 10 μM μM 10μM μM μM Glucose-6-phosphate 0 ND* 0 ND 0 ND dehydrogenase/glucosehexokinase Leukotriene A4 0 ND 4 ND 25 0 hydrolase Aminopeptidase N ND13 ND 12 14 3 Angiotensin converting 3  9 3  0 0 0 enzyme 1 *ND = notdetermined

Example 3

The effects of Compound 2 on performance in different memory tasks invivo were investigated.

Surgical Preparation of Rats

All experiments were performed according to the National Health andMedical Research Council of Australia “Code of practice for the care anduse of animals for scientific purposes”. Male Sprague Dawley rats,(250-270 g) are housed individually and given water and standard ratchow ad libitum. On the day of surgery, the rats were anaesthetized with5% isofluorane, placed in a stereotaxic frame and maintained on 2%isofluorane for the duration of the cannula implantation procedure. Therats were stereotaxically implanted with chronic indwelling cannula(Plastics One) into the cerebral lateral ventricles using the followingflat skull coordinates 0.8 mm posterior to Bregma, 1.55 mm lateral tomidline and 3.5 mm ventral to the dura. The cannula was then secured tothe skull with stainless steel screws and dental cement. Seven daysfollowing surgery, proper cannula placement was verified by a bolusinjection of angiotensin II (1 nmol/μl). Lack of a robust dipsogenicresponse within 5 min of angiotensin II administration would suggestmisplacement of the cannula and the animal was then excluded fromfurther studies.

Novel Object Recognition Task (Bevins et al, 2006)

The rats are allowed at least 5 days post-operative recovery prior touse in any behavioural paradigms. On the day of the acquisition trial,the rats were habituated for 5 min in the testing box (made from greyperspex of dimensions 60 cm width×60 cm length×50 cm height) in diffusedim light and then returned to their home cage. The animals were thenrested for at least 2 h and then injected with 1 nmol or 0.1 nmolCompound 2 in 2 μl of 10% dimethyl sulfoxide (DMSO). Control animalsreceived 2 μl of 10% DMSO. Following drug administration, the rats werereturned to their home cage for 5 min and then placed in the testing boxfacing the opposite direction to 2 identical objects that have beensecured to the floor in adjacent corners of the box. The rats wereallowed 5 min to explore the objects and the definition of explore isthat the animal's nose is less than 2 cm from object when it is facingthe object. Animals that displayed a lack of interest in the object,exploration time of less than 15 secs were excluded from the study atthis stage. The animals were then returned to their home cage during theintertrial interval of 20 h. On day 2 of testing, one of the objectswere replaced by a novel object made from the same material but of adifferent shape—the rats were given 2 mins in the box. The recognitionindex was determined as the time spent exploring the novel object minusthe time spent on the familiar object divided by the time spent on bothobject.

Spontaneous Alternation Plus Maze (McNay et al, 2000)

The plus maze was composed of four arms with each arm measuring 75×10×20cm. The floor and walls of the central platform and the floors of thearms were made of black plastic. Spontaneous alternation testing wasconducted by placing the rat on the center platform of the maze andallowing 20 min of unimpeded exploration. The number and sequence of armentries were recorded for calculation of a percent alternation score. Analternation consisted of 4 different arm choices of 5 consecutive armentries. A 4/5 alternation score was computed by dividing the number ofobserved alternations in overlapping quintuplets by the number ofpossible alternations and multiplying the quotient by 100.

Elevated Plus Maze

The elevated plus maze was used to investigate the potential effect ofIRAP inhibitors on stress or anxiety. The elevated plus maze consists oftwo open arms (70×10 cm) with a 5 cm high surrounding wall and twoenclosed arms (70×10 cm) with a 27 cm high surrounding wall. The floorof the open and closed arms are white laminate, the open arm walls areclear perspex, and the closed arms walls dark grey perspex. The maze iselevated 85 cm above the ground in the centre of a room that is lit byoverhead lights generating 124 lux. Naive rats, treated either with 1nmol Compound 2 dissolved in 10% DMSO or vehicle, were placed 5 minafter the icy injection, on the central platform facing one of theclosed arms and behaviour monitored for 10 min. The time spent in theclosed arms compared to the open arms was a measure of the anxietystatus of the animals.

Locomotor Cell Activity

Locomotor activity of rats treated with 1 nmol Compound 2intracerebrocentricularly was monitored in special cages measuring40×40×40 cm (Coulbourn Instruments, Philadelphia, USA) equipped withharmless infrared photobeams. Activity was measured when pairs ofphotobeams spaced 2.54 cm apart providing a 1.27 cm spatial resolutionwere crossed. Data was collected and analysed using TruScan Photo BeamActivity system (Coulbourn Instruments, Philadelphia, USA). Each rat wasplaced in the arena for 30 min.

The results are depicted in Tables 3-A1-3-A2 and 3-B1-3-B3.

Rats treated with Compound 2, at 1 and 0.1 nmoleintracerebroventricularly, exhibited better recognition of a novelobject after 24 h compared to vehicle treated control rats, n=10/groupand *p<0.05 (Table 3-A1). Rats treated with 0.1 nmole exhibitedsignificantly enhanced spontaneous alternation scores compared tovehicle treated control rats, n=8/group and **p<0.01 (Table 3-A2). Ratstreated with Compound 2 at 0.1 and 1 nmol intracerebroventricularly,were not significantly more or less stressed than vehicle treatedcontrol rats as determined by time spent in the open arm of the elevatedplus maze. n=8 per group (Table 3-B1). Rats treated with Compound 2 at0.1 and 1 nmol intracerebroventricularly, did not exhibit increased ordecreased locomotor activity compared to vehicle treated rats asdetermined by crossing of infrared beams and total distance travelled ina locomotor cell over a period of 30 mins. n=8 per group (Table 3-B2).

TABLE 3-A1 Treatment Recognition Index Vehicle 5.04 ± 5.43 0.1 nmol35.82 ± 7.30*   1 nmol 45.09 ± 9.97*

TABLE 3-A2 Treatment Spontaneous Alternation Score (%) Vehicle 62.07 ±1.55 0.1 nmol  73.70 ± 3.14**   1 nmol 64.34 ± 2.49

TABLE 3-B1 Treatment Time spent in the open arm (% control) Vehicle  100 ± 31.26 0.1 nmol 121.62 ± 28.26   1 nmol 127.88 ± 19.18

TABLE 3-B2 Treatment Distance travelled (% control) Vehicle 100 ± 3  0.1nmol 85.12 ± 12.99   1 nmol 90.16 ± 6.73 

Example 4

Hippocampal glucose uptake assay. Eight week old male Spraque-Dawleyrats were deeply anaesthetised with Isofluorothane and killed bydecapitation. The brains were rapidly removed and placed into ice-cold,95% O₂, 5% CO₂-bubbled artificial cerebrospinal fluid (aCSF: 124 mMNaCl, 2.5 mM KCl, 2 mM CaCl₂, 2 mM MgSO₄, 26 mM NaHCO₃, 1.25 mM NaH₂PO₄pH 7.4) supplemented with 10 mM D-glucose (Sigma). Under aCSF, thehippocampal hemispheres were rapidly dissected out and 200 μm slicesprepared on McIllwain tissue chopper with an ice-cold blade and stage.Slices from each hemisphere were kept together and transferred tofreshly 95% O₂, 5% CO₂-bubbled aCSF supplemented with 10 mM D-glucose at37° C. for 1 hour. All subsequent steps were carried out at 37° C. in agently shaking chamber with continuous infusion of 95% O₂, 5% CO₂.Slices from one hemisphere were used as a basal control while slicesfrom the other hemisphere were stimulated, providing an internal controlfor each animal. Hemisphere pairs were transferred to 95% O₂, 5% CO₂bubbled aCSF supplemented with 0.1 mM D-glucose and 2 mM 2-deoxyglucoseand 1 mM dbCAMP for 15 min following which slices from one hemispherewere stimulated by the addition of 100 nM HFI419 while the otherhemisphere provided an internal control for each animal and 0.1 μCi2-Deoxy-d-[2,6-³H]glucose (³H-2DG) (specific activity 49 Ci/mmol;Amersham Biosciences, NSW, Australia) was added to a final concentrationof 0.1 μM in both basal and stimulated hemispheres for five minutes.Following uptake, hemispheres were rapidly rinsed in four changes of icecold PBS and slices transferred to pre-weighed filter paper and allowedto dry. Dried slices from each hemisphere were weighed and solubilizedovernight with Soluene-350 (Perkin Elmer, MO, USA). Tritium content wasmeasured in a Liquid Scintillation Analyser 1900TR (Perkin Elmer, MA,USA).

An increase in dibutyryl cAMP-evoked glucose uptake in response toCompound 2 was observed.

The results are depicted in Table 4-1.

The effect of Compound 2 was tested in vitro on the metabolic demands ofneurones.

TABLE 4-1 Fold change in 3H-2DOG uptake dbcAMP 1 dbcAMP & Compound 2 1.7

BIBLIOGRAPHY

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1. A compound of Formula (I)

wherein: A is pyridyl which may be optionally substituted; R¹ is NHCOR⁸;X is O; R⁸ is selected from hydrogen, optionally substituted alkyl andoptionally substituted aryl; R² is CN, CO₂R⁹, C(O)O(O)R⁹, C(O)R⁹ orC(O)NR⁹R¹⁰ wherein R⁹ and R¹⁰ are independently selected from alkyl,alkenyl, alkynyl, aryl, heteroaryl, carbocyclyl, heterocyclyl, each ofwhich may be optionally substituted, and hydrogen; or R⁹ and R¹⁰,together with the nitrogen atom to which they are attached, form a3-8-membered ring which may be optionally substituted; R³-R⁶ areindependently selected from hydrogen, halo, nitro, cyano alkyl, alkenyl,alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl, hydroxy, alkoxy,alkenyloxy, alkynyloxy, alkynyloxy, aryloxy, heteroaryloxy,heterocyclyloxy, amino, acyl, acyloxy, carboxy, carboxyester,methylenedioxy, amido, thio, alkylthio, alkenylthio, alkynylthio,arylthio, heteroarylthio, heterocyclylthio, carbocyclylthio, acylthioand azido, each of which may be optionally substituted whereappropriate, or any two adjacent R³-R⁶, together with the atoms to whichthey are attached, form a 3-8-membered ring which may be optionallysubstituted; and Y is hydrogen or C₁₋₁₀alkyl, or a pharmaceuticallyacceptable salt thereof.
 2. A compound according to claim 1 wherein R¹is NHCOC₁₋₆alkyl, NHCOphenyl or NHCObenzyl.
 3. The compound of claim 1,wherein the compound is Ethyl2-(acetylamino)-7-hydroxy-4-pyridin-3-yl-4H-chromene-3-carboxylate or apharmaceutically acceptable salt thereof.
 4. A composition comprising acompound according to claim 1 together with a pharmaceuticallyacceptable carrier or excipient.
 5. The compound of claim 1, wherein R²is CO₂R⁹ and R³-R⁶ are selected from hydrogen, hydroxy, acyl, acyloxy,carboxy and carboxyester.